Interlayer for laminated glass and laminated glass

ABSTRACT

The present invention provides an interlayer for a laminated glass which does not give rise to the moiré phenomenon even when the arrangement and pitch of its embossments are orderly, hence providing for good workability in cutting and laminationg operations and good deaeration in preliminary contact bonding, thus insuring the production of a laminated glass of high quality with a minimum of rejects for reasons of air bubbles, and a laminated glass containing said interlayer. The invention also provides an interlayer for a laminated glass which provides for good deaeration without a risk for premature margial sealing even if the temperature at initiation of deaeration at preliminary contact bonding is not critically controlled and which does not require raising of temperature for achieving a marginal seal of the glass-interlayer assembly, and a laminated glass containing said interlayer.

This is a divisional of application Ser. No. 10/786,367 filed Feb. 26,2004; which is a divisional of Ser. No. 10/019,656 filed Feb. 12, 2002now U.S. Pat. No. 6,863,956; which is a §371 National Stage Applicationof PCT Application No. PCT/JP00/04383 filed Jul. 3, 2000, now U.S. Pat.No. 6,863,956; the disclosure of which is incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to an interlayer for a laminated glassproviding for improved deaeration and a laminated glass comprising thesame.

BACKGROUND ART

The laminated glass manufactured by interposing an interlayer comprisinga sheet made of a thermoplastic resin such as plasticized polyvinylbutyral between glass sheets and bonding them together into an integralunit is in broad use for glazing the windows of automobiles, aircraft,and buildings.

When such a laminated glass is subjected to an external impact, theglass may break up but the interlayer sandwiched between the componentglass sheets will not readily be destroyed and even after breakage, theglass remains glued to the interlayer so that its fragments will not bescattered. Therefore, the bodies of men in the vehicle or building areprotected against the injury by fragments of the broken glass.

Such a laminated glass is usually manufactured by interposing aninterlayer between glass sheets, drawing the whole over a nip roll orplacing it in a rubber bag and evacuating the bag to effect preliminarycontact bonding with concurrent removal of the residual air entrappedbetween the glass and the interlayer under suction, and finally carryingout final contact bonding at elevated temperature and pressure in anautoclave.

The interlayer mentioned above is required to satisfy not only the basicperformance requirements such as good clarity, bond ability, bulletresistance, weather resistance, etc. but also the requirement that itdoes not undergo blocking during storage, the requirement that itprovides for good workability in the insertion thereof between glasssheets, and the requirement that it lends itself to efficient deaerationin preliminary contact bonding so that the formation of bubbles byentrapment of air may be precluded.

To satisfy the above requirements, it is common practice to provide bothsurfaces of an interlayer with many embossment patterns comprising fineconvex portions and concave portions. As the geometry of such concaveand convex portions, there are disclosed a variety of embossmentgeometries each containing a multiplicity of concave portions and thecorresponding multiplicity of concave portions, and a variety ofgeometries each containing a multiplicity of ridges and thecorresponding multiplicity of troughs.

The morphological parameters of an embossment design, such ascoarseness, arrangement and relative size, have also been explored andJapanese Kokoku Publication Hei-1-32776 discloses “a thermoplastic resininterlayer comprising a flexible thermoplastic resin film or sheethaving a fine concavo-convex (embossed) surface pattern for use as aninterlayer for lamination characterized in that at least one side ofwhich is provided with a multiplicity of discrete protruded portionsintegral with the film or sheet, with all the concave portionscomplementary to said protruded portions forming a continuum on the samelevel.”

However, when such an orderly embossment pattern is generally formed onboth sides of the interlayer, the mutual interference of the diffractingsurfaces gives rise to a streaks-like diffraction image known generallyas the “moiré phenomenon”.

Furthermore, since the conventional embossment pattern is generallyprovided in a random fashion by using sand blasted roll, it hardlyprovides for sufficient deaeration.

The moiré phenomenon mentioned above is not only undesirable fromappearance points of view but the attention-distracting change of theinterference fringes causes an eye strain and motion sickness-likesymptoms in the working personnel involved in interlayer cutting andlaminating operations, thus leading to the problem of poor workability.Moreover, even in the case of an interlayer provided with an orderlyembossment pattern only on one side, the operation involving thestacking of a plurality of interlayer sheets causes appearance of themoiré phenomenon, thus detracting from workability in a similar manner.

The moiré phenomenon is more liable to occur when the arrangement andpitch of the embossed pattern formed on the surface of an interlayer aremore orderly, and in cases where the arrangement is such that thedistance between at least two points of the convex portions ofrespective embossments is constant or where the arrangement of theembossment-pattern on both sides of the interlayer are identical, themoiré phenomenon occurs in most instances.

Therefore, such embossment patterns as a grid pattern, a stripe pattern,and a radiant pattern having a constant angular pitch may be mentionedas representative embossment patterns liable to give rise to the moiréphenomenon.

To overcome this disadvantage of the above moiré phenomenon and theassociated deterioration of workability, Japanese Kokai PublicationHei-5-294679, for instance, discloses “a method which comprisesproviding the surface of an interlayer with a multiplicity of protrudedportions in a controlled pattern and further with an embossment patternof convex portions finer than these protruded portions in a randompattern.”

It is true that the above method contributes in a considerable measureto attenuation of the above moiré phenomenon but since the embossmentpattern of finer convex portions is formed to extend not only tosurfaces of the larger protruded portions but also surfaces not formedwith the larger protruded portions, the pooling of air occurs in concaveportions of the embossment between the finer convex portions so that thedeaeration in preliminary contact bonding becomes insufficient as adisadvantage.

Further, Japanese Kohyo Publication Hei-9-508078 discloses an interlayerhaving embossment patterns each having an orderly array of troughs, thepattern on one side being displaced from that on the other side by notless than 25 degrees, more preferably by 90 degrees, to thereby obviatethe moiré phenomenon.

It is known, in the above technology, that the linear designs displacedby 90 degrees for obviating the moiré phenomenon can be imparted by theheat transfer technique using a roll having engraved lines of 45degrees. However, the larger the angle of engraved lines of the roll is,the less easy is the heat transfer to be effected. Generally speaking, apattern of longitudinally parallel lines with respect to the flow oftransfer can be most easily formed and a pattern of transverse linesrequires transfer temperature control as well as a high transferpressure.

Furthermore, in the above technology, unless the temperature atinitiation of deaeration in preliminary contact bonding is criticallycontrolled, a premature sealing of the marginal part of theglass-interlayer assembly (e.g. glass/interlayer/glass), i.e. prematuremarginal sealing, takes place, with the result that the deaeration ofthe central part of the assembly becomes still more inadequate.

As a measure to prevent the above premature marginal sealing, there isknown the method which comprises controlling the temperature atinitiation of deaeration according to the size of troughs to therebyprevent said premature sealing at the pressure bonding of the assemblyor the method which comprises increasing the coarseness of embossment.However, there is the problem that in order to achieve a positivemarginal seal of the laminate, the temperature for preliminary contactbonding must be considerably raised.

Furthermore, if the linear designs on both sides of the interlayer aremade parallel from moldability considerations, the problem will arisethat the handleability of the interlayer particularly in terms ofself-adhesiveness is adversely affected, i.e. the self-adhesion of theinterlayer is increased.

In fact, the above prior art interlayer has been fairly improved in thetendency toward blocking during storage, handling workability, and theefficiency of deaeration in preliminary contact bonding but in theproduction of a laminated glass having a large surface area or alaminated glass with a large radius of curvature or in carrying outdeaeration under the stringent conditions imposed by circumstancescalling for increased productivity of laminated glass, for instance,there is the problem that the deaeration and sealing effects are not sosatisfactory as desired.

Thus, when deaeration is to be carried out under such stringentconditions, it is difficult, in particular, to establish a uniform sealbetween the sheet glass and interlayer all over the area and, hence,deaeration and sealing become insufficient, with the result that in thefinal contact bonding performed under heat and pressure in an autoclave,pressurized air infiltrates through the seal defect to form air bubblesbetween the glass and the interlayer, thus frustrating to produce alaminated glass of high transparency.

The problem of such a seal defect can be resolved to a certain extent bystrictly controlling preliminary contact bonding conditions within acertain very narrow range but the compatible temperature range is sonarrow that the incidence of rejects due to air bubble formation isincreased.

Moreover, when a laminated glass is manufactured using an interlayersuch that both the geometry of embosses and the level of depressions areuniform all over as described in the above disclosure, the variation inthickness of the very interlayer film and the pair thickness differenceconsisting of the difference in thickness or the difference in theradius of curvature of the glass to be laminated cannot be sufficientlyabsorbed.

In addition, in the case of the prior art interlayer, it is necessary toprepare a large number of embossing rolls having different designscorresponding to various processing needs of users and manufacture manykinds of interlayer films embossed to various three-dimensional patternscompatible with the respective users' processing conditions, this beinginefficient from productivity points of view.

Furthermore, when the preliminary contact bonding process involvingdeaeration by draw deaeration is compared with the process involvingdeaeration by vacuum deaeration, there is a marked difference in theconditions of deaeration, viz. whereas deaeration is effected at anelevated pressure in the former process, it is effected at a negativepressure in the latter process, so that in establishments having onlyone kind of equipment, there are cases in which preliminary contactbonding cannot be carried out.

As mentioned hereinbefore, the preliminary contact bonding technologyinvolving deaeration is generally classified into a draw deaerationmethod in which the glass-interlayer assembly is drawn over a rubberroll and a vacuum deaeration method in which the assembly is placed in arubber bag and subjected to a negative pressure to bleed air from themargin of the glass-interlayer assembly.

In the deaeration method involving the use of a negative pressure, theprocess starts with placing the glass/interlayer/glass assembly in asufficiently cooled (e.g. 20° C.) rubber bag and starting deaeration.The vacuum hold time is set to about 10 minutes and after the air issufficiently removed from the whole glass/interlayer/glass assembly, thetemperature is raised to heat the assembly to about 110° C. By thisprocedure, the interlayer and glass are bonded almost completely tight.Then, the assembly is cooled to the neighborhood of room temperature andthe preliminary laminated glass thus obtained is taken out andtransferred to the final contact bonding stage.

When the vacuum deaeration method is adopted in the preliminary contactbonding stage, which comprises the above cycle of heating and cooling,it is necessary for enhanced productivity to set the initial temperaturewithin the rubber bag at a high level and set the ultimate temperatureat a low level.

However, when the initial temperature within the rubber bag is set high,the marginal part of the assembly is the first to succumb to thepressure of contact bonding so that the air in the central part isprevented from escaping efficiently but remains entrapped. If thedeaeration is sufficient in the preliminary contact bonding stage, anyresidual air, which is small in amount, is allowed to dissolve in theinterlayer in the final contact bonding stage (e.g. 130° C.×1.3 MPa×1hr), with the result that a transparent laminated glass can be obtained.However, if the residual amount of air is large, the air will not becompletely dissolved in the final contact bonding stage so that airbubbles appear in the product laminated glass. On the other hand, if theultimate temperature is set too low, an incomplete seal occurs locallyin the marginal region and as the pressurized air finds its way intosuch localities in the final contact bonding stage, air bubbles areproduced in the product laminate.

Another factor contributory to the above phenomenon is that, in alaminated glass of the glass/interlayer/glass construction, there occurareas where one of the glass sheets is urged toward the other glasssheet and areas where one of the glass sheets is urged away from theother glass sheet depending on the accuracy of glass bending and the wayin which the gravity of glass acts.

The geometry of embossed surface irregularities proposed so far includesrandom geometries (a hill and a valley are alternating) and orderlygeometries comprising quadrangular pyramids or triangular pyramids. Inaddition, as applicable to the vacuum deaeration method, Japanese KohyoPublication Hei-9-508078 teaches that providing a route for escape ofair by means of troughs is effective in preventing the premature sealingin the course of deaeration.

This method, however, has the disadvantage that while the initialtemperature within the rubber bag can be set high, the ultimatetemperature must also be set high and if the ultimate temperature is setlow, the infiltration of air will occur in the final contact bondingstage to cause air bubbles. Thus, in the case of the conventional randomembossments, the heating may be carried out simply from an initialtemperature of 20° C. to an ultimate temperature of 85° C. In the methodreferred to above, however, the formation of air bubbles cannot beavoided unless the heating is performed from an initial temperature of35° C. to an ultimate temperature of 95° C. so that even if the depth(height), width, and pitch of troughs or ridges are optimized, theembossments must be collapsed to a certain volume. Consequently, theinitial temperature and the ultimate temperature must be shifted upwardalmost in parallel, with the result that the effect of increasing theproductivity of preliminary contact bonding, which is a deaerationprocess, is small.

SUMMARY OF INVENTION

In the above state of the art, the present invention has for its objectto provide an interlayer for a laminated glass which does not give riseto the moiré phenomenon even when the arrangement and pitch of itsembossments are orderly, hence providing for good workability in cuttingand laminating operations and good deaeration in preliminary contactbonding, thus insuring the production of a laminated glass of highquality with a minimum of rejects for reasons of air bubbles, and alaminated glass containing said interlayer.

The invention has for its further object to provide an interlayer for alaminated glass which provides for good deaeration without a risk forpremature marginal sealing even if the temperature at initiation ofdeaeration at preliminary contact bonding is not critically controlledand which does not require raising of temperature for achieving amarginal seal of the glass-interlayer assembly, and a laminated glasscontaining said interlayer.

The present invention has for its still further object to provide aninterlayer for a laminated glass which is satisfactory in the resistanceto blocking during storage, handling work ability and productivity inthe processing of glass, as well as deaeration and sealing properties atpreliminary contact bonding and which is capable of adapting itself withease and efficiently to varied processing needs of various users, and alaminated glass containing said interlayer.

The present invention is directed to an interlayer for a laminated glasswhich comprises a thermoplastic resin sheet provided with embossmentscomprising concave portions and convex portions on both sides thereof(hereinafter referred to sometimes as “interlayer”).

The first aspect of the present invention is concerned with aninterlayer for a laminated glass in which a pitch of embossments on oneside is different from a pitch of embossments on the other side.

In accordance with the first aspect of the invention, it is preferablethat concave portions on at least one side are continual and it is morepreferable that bottoms of concave portions on at least one side arecontinual.

In this first aspect of the invention, it is preferable that the pitch(L1) of embossments on one side and the pitch (L2) of embossments on theother side satisfy the relation of (L1)<(L2), and the proportion ofexistence of a convex portion on the other side within the range(L1×0.25) of before and after a position of a convex portion on one sideis not more than 50% of the number of convex portions on one side.

In the first aspect of the invention, it is further preferable thatconcave portions on at least one side are provided in a linear pattern.

The second aspect of the present invention is an interlayer for alaminated glass in which said concave portions on at least one side havea trough-like geometry with a continual bottom while said convex portionon the same side has a plateau-forming top.

In the second aspect of the present invention, it is preferable thatfine concave and convex portions are provided on the plateau-forming topsurface of the convex portion.

In the second aspect of the invention, a surface roughness Ra of theplateau-forming top surface is preferably not less than 2.5 μm, morepreferably not less than 3.0 μm.

In the second aspect of the invention, a width of the plateau-formingtop surface is preferably not less than 20% of a pitch of convexportions.

In the second aspect of the invention, the width of the plateau-formingtop surface may be constant or random.

The third aspect of the present invention is concerned with aninterlayer for a laminated glass in which said concave portions on atleast one side have a trough-like geometry, and segmenting walls areformed within said trough-like geometry.

In the third aspect of the invention, a height of the segmenting wall ispreferably smaller than a depth of the trough.

In the third aspect of the invention, the segmenting walls arepreferably arranged at equal intervals.

The fourth aspect of the present invention is an interlayer for alaminated glass in which said concave portions on at least one side havea trough-like geometry and are not on one and the same level, and aratio of a surface roughness (Rz) and a surface roughness (Rzv) of anegative model is Rzv/Rz≧0.25 on at least one side.

In the fourth aspect of the invention, troughs may be provided in alinear configuration or a grid configuration.

The fifth aspect of the present invention is concerned with aninterlayer for a laminated glass in which said concave portions on atleast one side have a continual trough-like geometry, and said convexportion on the same side has segmenting troughs while a bottom of saidsegmenting trough is not on one and the same level as a bottom of thecontinual trough-like geometry of said concave portion.

In the firth aspect of the invention, the trough-like geometry of theconcave portion and segmenting troughs of said convex portion may beprovided in a grid configuration or a in random configuration.

In the fifth aspect of the invention, a depth of segmenting troughs ofthe convex portion may be uniform or random.

The sixth aspect of the present invention is concerned with aninterlayer for a laminated glass in which at least one side is providedwith concave troughs, and an angle between said concave trough and adirection of extrusion of said thermoplastic resin sheet is less than25°.

The seventh aspect of the present invention is concerned with aninterlayer for a laminated glass in which said concave portions on atleast one side have a trough-like geometry, and said trough-likegeometry is constant in sectional area while has a depth distribution oftroughs having a depth of not less than 5% of the maximum trough depth.

In the seventh aspect of the invention, troughs having the depth of notless than 5% of the maximum trough depth are preferably provided at apitch of not more than 10 mm.

In the seventh aspect of the invention, the trough-like geometry ispreferably provided in parallel with the direction of flow of theinterlayer for a laminated glass.

In the present invention, the thermoplastic resin sheet is preferably aplasticized polyvinyl acetal resin sheet.

A laminated glass obtainable by interposing the interlayer for alaminated glass according to the invention between at least one pair ofglass sheets and consolidating them into an integral unit alsoconstitutes one aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating the embossment pattern of theinterlayer for a laminated glass according to Examples 1 to 3.

FIG. 2 is a schematic diagram illustrating the embossment pattern of theinterlayer for a laminated glass according to Comparative Example 1.

FIG. 3 is a schematic diagram illustrating the embossment pattern of theinterlayer for a laminated glass according to Example 4.

FIG. 4 is a schematic diagram illustrating the embossment pattern of theinterlayer for a laminated glass according to Example 5.

FIG. 5 is a schematic diagram illustrating the embossment pattern of theinterlayer for a laminated glass according to Example 6.

FIG. 6 is a schematic diagram illustrating the embossment pattern of theinterlayer for a laminated glass according to Comparative Example 2.

FIG. 7 is a schematic diagram illustrating the embossment pattern(concave and convex patterns) of the interlayers for laminated glasswhich are obtained in Examples 8 and 9.

FIG. 8 is a schematic diagram illustrating the embossment pattern(concave and convex patterns) of the interlayers for laminated glasswhich are obtained in Examples 10 and 11.

FIG. 9 is a schematic diagram illustrating the embossment pattern(concave and convex patterns) of the interlayer for a laminated glasswhich is obtained in Comparative Example 3.

FIG. 10 is a schematic diagram illustrating the embossment pattern(concave and convex patterns) of the interlayers for laminated glasswhich are obtained in Examples 12 and 13.

FIG. 11 is a schematic diagram illustrating the embossment pattern(concave and convex patterns) of the interlayers for laminated glasswhich are obtained in Examples 14 and 15.

FIG. 12 is a schematic diagram illustrating the embossment pattern(concave and convex patterns) of the interlayer for a laminated glasswhich is obtained in Example 16.

FIG. 13 is a schematic diagram illustrating the embossment pattern(concave and convex patterns) of the interlayer for a laminated glasswhich is obtained in Comparative Example 4.

Referring to FIG. 7 to FIG. 13, a represents the pitch of convexportions, b represents the width of the plateau-forming top surface ofthe convex portion, and c represents the width of the concave portion.

FIG. 14 is a schematic diagram illustrating the embossment pattern(concave and convex patterns) of the interlayers for laminated glasswhich are obtained in Examples 17 and 18.

FIG. 15 is a schematic diagram illustrating the embossment pattern(concave and convex patterns) of the interlayers for laminated glasswhich are obtained in Examples 19 and 20.

FIG. 16 is a schematic diagram illustrating the embossment pattern(concave and convex patterns) of the interlayer for a laminated glasswhich is obtained in Comparative Example 5.

FIG. 17 is a perspective view showing a wedge-shaped tracer (tip width1000 μm, opposite face angle 90°) for use in Rzv measurement.

FIG. 18 is a perspective view showing the embossment pattern of theinterlayer for a laminated glass according to the fifth aspect of theinvention.

FIG. 19 is a plan view showing the embossment pattern of the interlayerfor a laminated glass according to the fifth aspect of the invention.

Referring to FIG. 18 and FIG. 19, 1 represents the trough-likeconfiguration of the concave portion, 2-represents the segmentingtroughs of the convex portion, and 3 represents the depth of segmentingtroughs of the convex portion.

FIG. 20 shows an interlayer for a laminated glass according to the sixthaspect of the invention, where (a) is a plan view and (b) is a sideelevation view.

Referring to FIG. 20, 4 represents a concave trough and 5 represents anembossment.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is now described in detail.

The interlayer of the invention comprises a thermoplastic resin sheet.

As the thermoplastic resin sheet to be used in the invention, any of theknown sheets available for use as laminated glass interlayers can beutilized; thus, for example, plasticized polyvinyl acetal resin sheet,polyurethane resin sheet, ethylene-vinyl acetate resin sheet,ethylene-ethyl acrylate resin sheet, and plasticized vinyl chlorideresin sheet can be mentioned. While these thermoplastic resin sheets arequite satisfactory in the basic properties required of a laminated glassinterlayer, such as adhesion, weather resistance, bullet resistance,transparency, etc., the plasticized polyvinyl acetal resin sheetrepresented by plasticized polyvinyl butyral resin sheet can be usedwith particular advantage.

The plasticized polyvinyl acetal resin mentioned above is preferably aresin composition predominantly composed of polyvinyl acetal resin andas the polyvinyl acetal resin, a polyvinyl butyral resin having abutyralization degree of 60 to 70 mol % and a polymerization degree of1000 to 2000, for instance, can be used with advantage.

The plasticizer which can be used for said plasticized polyvinyl acetalresin sheet includes ethylene glycol di-2-ethyl butyrate, 1,3-propyleneglycol di-2-ethylbutyrate, 1,4-propylene glycol di-2-ethylbutyrate,1,4-butylene glycol di-2-ethylbutyrate, 1,2-butylene glycoldi-2-ethylbutyrate, diethylene glycol di-2-ethylbutyrate, diethyleneglycol di-2-ethylhexoate, dipropylene glycol di-2-ethylbutyrate,triethylene gycol di-2-ethylpentoate, triethylene glycoldi-2-ethylhexoate, tetraethylene glycol di-2-ethylbutyrate, diethyleneglycol dicaprylate, and triethylene glycol dicaprylate.

In the present invention, the addition level of such plasticizer ispreferably within the range of 20 to 60 parts by weight per 100 parts byweight of polyvinyl acetal resin.

Furthermore, where necessary, the interlayer according to the inventionmay contain various additives such as heat stabilizer, ultravioletabsorber, adhesion modulating agent, and so forth.

The thickness of said thermoplastic resin sheet can be selectedaccordingly in consideration of the bullet resistance and otherproperties required of laminated glass and is not particularlyrestricted but, just as it is the case with the conventional interlayer,the preferred thickness is 0.2 to 2 mm.

For use as the interlayer according to the invention, said thermoplasticresin sheet is provided with embossments comprising concave portions andconvex portions on both sides.

Unless the parameters specific to the respective aspects of theinvention are dissatisfied, the above embossment pattern is notparticularly restricted but encompasses a variety of concave and convexpatterns having multiplicities of convex portions and complementaryconcave portions. The distribution of such convex and concave patternsmay be orderly or random, although an orderly distribution is preferred.

The above convex portions may be equal or varying in height and thecorresponding concave portions may also be equal or varying in depth.

Unless the parameters specific to the respective aspects of theinvention are dissatisfied, the geometry of the above convex portion isnot particularly restricted but includes various cones inclusive oftriangular pyramid, quadrangular pyramid, circular cone, etc.; truncatedcones such as truncated triangular pyramid, truncated quadrangularpyramid, truncated circular cone, etc.; and pseudocones having a hill orhemispherical head. The geometry of the above concave portion iscomplementary to that of said convex portion.

The technology of forming the embossment includes the embossing rollmethod, calender roll method, contour extrusion method, andextrusion-lip embossing method which takes advantage of melt fracture,among others. Particularly preferred among them is the embossing rollmethod by which an embossment quantitatively comprising constant andfine concave and convex portions can be produced.

The embossing roll for use in the above embossing roll method includesthe one manufactured by subjecting the surface of a metal roll toblasting with grits of aluminum oxide, silicon lo oxide or the like and,then, to lapping with a vertical grinder or the like to reduce excessivesurface peaks to thereby form a fine embossment pattern (concave andconvex patterns) on the roll surface, the one obtained by using anengraving mill (mother mill) and transferring the embossment pattern(concave and convex patterns) of this engraving mill to the surface of ametal roll to produce a fine embossment pattern (concave and convexpatterns) on the roll surface, and the one obtained by forming a fineembossing pattern (concave and convex patterns) on the surface of a rollby etching, among other methods.

Referring to the geometry of said embossment, the ease of release of airin deaeration at the preliminary contact bonding between the glass sheetand the interlayer is related to the continuity of the concave portionsof the concavo-convex configuration, and the pitch and arrangement ofconcave portions have no important bearing on the ease of escape of air.In the early phase of deaeration, the air in the concave portion of theconcavo-convex configuration flows from the interface with the glassselectively into the trough comprised of the concave portions. Then, theair in the trough is forced out via the trough and the amount of airthat remains in the trough is of the order which the interlayer cansufficiently absorb.

The dimensions of the above convex portion and of the above concaveportion are not particularly restricted unless the parameters specificto the respective aspects of the invention are dissatisfied but theinterval (pitch) of convex portions is preferably 10 μm to 1 cm, morepreferably 50 to 1000 μm, particularly preferably 200 to 800 μm. Withinthe range of 200 to 800 μm, a still greater improvement in clarity isobtained. The height of the convex portion is preferably 5 to 500 μm,more preferably 20 to 100 μm. Furthermore, the length of the bottom ofeach convex portion is preferably 30 to 1000 μm. It should be understoodthat the term “pitch” as used in this specification means the distancefrom the center of a convex or concave portion to the center of theadjacent convex or concave portion.

The collapsibility of the embossment at preliminary contact bonding islargely dependent on the volume of the embossment. The determinants ofthe volume of embossments are the pitch and arrangement of convexportions and the expanse of the plateau-forming top of the convexportion. The larger the plateau-forming top of the convex portion is,the larger is the volume of embossments that can be established and,hence, the degree of coarseness of embossing can be smaller. When alarge embossment volume can be set, there can be obtained an interlayerfor a laminated glass which is free from the problem of prematuresealing. At the temperature necessary for marginal sealing atpreliminary contact bonding, the interlayer for a laminated glassbecomes sufficiently fluid so that insofar as the coarseness ofembossment is within a given range, the margin can be sufficientlysealed.

The first aspect of the present invention is concerned with aninterlayer for a laminated glass in which a pitch of embossments on oneside is different from a pitch of embossments on the other side.

By embossing in such manner that the pitch of embossments on one side ofthe interlayer is different from the pitch of embossments on the otherside in accordance with the first aspect of the invention, appearance ofsaid moiré phenomenon can be effectively inhibited even if thearrangement and pitch of embossments are comparatively orderly.

Generally speaking, appearance of the moiré phenomenon is liable tooccur when the embossments on the both sides of an interlayer are nearlyidentical in arrangement and pitch. Therefore, by embossing in suchmanner that the pitch of embossment is different from the pitch on theother side, that is to say by creating a difference between the pitch ofembossments on one side and the pitch of embossments on the other sideintentionally, it becomes possible to effectively inhibit appearance ofthe moiré phenomenon even when the arrangement and pitch of embosses oneach side are comparatively orderly.

In the first aspect of the invention, it is preferable that the concaveportions on at least one side are continual.

By insuring that the concave portions of the embossment on at least oneside of an interlayer is continual, the concave portions of theembossment become intercommunicable so that the efficiency of deaerationin preliminary contact bonding is remarkably improved and, hence, theresulting laminated glass will be of high quality with a minimizedincidence of rejects for reasons of inclusion of air bubbles.Furthermore, it is more preferable that the bottoms of the concaveportion on at least one side of the interlayer are continual.

In the first aspect of the invention, the pitch of embossments on oneside of the interlayer is preferably not less than 1.25 times the pitchof embossments on the other side. If the pitch of embossments on oneside is smaller than 1.25 times the pitch of embossments on the otherside, the inhibitory effect on appearance of the moiré phenomenon tendsto be insufficient. The more preferred ratio is not less than 1.3 times.

Furthermore, in the first aspect of the invention, it is preferable thatthe pitch (L1) of embossments on one side and the pitch (L2) ofembossments on the other side satisfy the relation of (L1)<(L2), and theproportion of existence of a convex portion on the other side within therange (L1×0.25) of before and after a position of a convex portion onone side is not more than 50% of the number of convex portions on oneside. When the convex portions satisfy the topological conditionsdefined above, the concave portions also satisfy the above topologicalconditions. Thus, the proportion of existence of a concave portion onthe other side within the range (L1×0.25) of before and after theposition of a concave portion on one side is preferably not more than50% of the number of concave portions on one side. As used in thisspecification, the term “position of a convex portion or a concaveportion” means the position of the center of the convex or concaveportion and the term “existence of a convex portion or a concaveportion” means the existence of the center of a convex or concaveportion. When the embossment on one side and the embossment on the otherside are arranged to satisfy the above requirement, appearance of themoiré phenomenon can be effectively inhibited. The more preferredproportion is not more than 30%, the still more preferred proportion isnot more than 10%, and the particularly preferred proportion is 0%, thatis the case where, within the range (L1×0.25) of before and after theposition of a convex or concave portion on one side, there exists not asingle convex portion or concave-portion, as the case may be, on theother side.

Furthermore, in the first aspect of the present invention, it ispreferable that the concave portions on at least one side are providedin a linear pattern.

While the emboss pattern of depressions is not limited to a linear onebut may for example be a grid pattern, a radiant pattern, or ahemispherical pattern, a further improvement in the deaerationefficiency at preliminary contact bonding can be realized by adopting alinear pattern for concave portions on at least one side of theinterlayer.

In the first aspect of the invention, it is so arranged that the pitchof embossments on one side is different from the pitch of embossments onthe other side. As this difference is intentionally created between thepitch of embossments on one side and the pitch of embosses pattern onthe other side, the moiré phenomenon does not take place even when thearrangement and pitch of embosses are orderly, so that the workabilityin cutting and laminating operations are improved.

Furthermore, when the embossment is such that the concave portions on atleast one side are continual, the concave portions of the embossment areintercommunicable so that the deaeration efficiency at preliminarycontact bonding in laminated glass processing is improved. Therefore,the resulting laminated glass is of high quality with a minimizedincidence of rejects for reasons of inclusion of air bubbles.

In addition, by carrying out embossing in such manner that the pitch ofthe embossments on one side will be not smaller than 1.25 times thepitch of the embossments on the other side or the proportion ofexistence of a convex portion on the other side within the range(L1×0.25) of before and after the position of a convex portion on oneside will be not more than 50% of the number of convex portions on oneside, the inhibitory effect on the moiré phenomenon is still furtherimproved.

Furthermore, by embossing in such a manner that the pattern of concaveportions on at least one side will be a linear pattern, the deaerationefficiency-improving effect is further enhanced.

The second aspect of the invention is concerned with an interlayer for alaminated glass in which the concave portion on at least one side has atrough-like geometry with a continual bottom while the convex portion onthe same side has a plateau-forming top.

In the second aspect of the invention in which the concave portion on atleast one side has a trough-like geometry with a continual bottom, amarked improvement in deaeration efficiency can be realized.

Furthermore, in this second aspect of the invention, the projecting topof the convex portion is flattened. The larger the area of theplateau-forming top is, the larger is the volume of convex portions ofthe embossment, with the result that the average surface roughness ofthe emboss can be relatively reduced and, hence, said premature marginalsealing of the glass-interlayer assembly in the preliminary contactbonding stage can be effectively prevented. Moreover, the interlayerwill be sufficiently fluid at the ordinary temperature which isnecessary for effecting a marginal seal of the glass-interlayer assemblyin the preliminary contact bonding stage and, therefore, to effect asufficient marginal seal at such an ordinary temperature, the averagesurface roughness of the embossment is preferably not greater than 100μm, more preferably not greater than 70μm.

Since, in the second aspect of the invention, the concave portion on atleast one side has a trough-like geometry with a continual bottom whilethe convex portion on the same side has the plateau-forming top, thesection perpendicular to the direction of extension of the convexportion has a trapezoid configuration with an increased top area of theconvex portion and the consequently increased volume of the convexportion so that the premature marginal sealing of the glass-interlayerassembly is effectively precluded in the preliminary contact bondingstage. Therefore, the air present in the central area of theglass-interlayer assembly can be effectively removed in the preliminarycontact bonding stage.

The above-mentioned convex portion preferably has fine concave andconvex portions on the plateau-forming top surface. Flattening the topof the convex portion may result in an increased self-adhesion of theinterlayer but this self-adhesion can be suppressed for improvedhandleability by forming such fine concave and convex portions on saidplateau.

The surface roughness of said top surface is preferably not less thanRa=2.5 μm. When Ra is not less than 2.5 μm, the sheet-to-sheet contactarea of the interlayer is so small that even when the interlayer isstored as a stack in the conventional manner, self-adhesion will not bea matter of concern. More preferably, Ra is not less than 3.0μm.

FIG. 7 is a schematic diagram showing the emboss pattern (concave andconvex patterns) of the interlayers obtained in Example 8 and Example 9which are described hereinafter. In FIG. 7, a represents the interval(pitch) of convex portions of the embossment and b represents the widthof the plateau-forming top of the convex portion of the embossment.

In the second aspect of the invention, said width (b) of the plateau ispreferably not less than 20% of the pitch of convex portions, i.e. b/ais preferably not less than 20%. If b/a is less than 20%, there may notbe obtained a sufficient increase in said volume of convex portions sothat said premature marginal sealing may not be well inhibited. On theother hand, if b/a is as great as 100%, there will exist substantiallyno concave portion of the embossment. Therefore, b/a is preferably lessthan 100%, more preferably not more than 90%.

Moreover, in the second aspect of the invention, the width of saidplateau may all be constant or may vary locally, i.e. may be of randomwidth.

In the second aspect of the invention, it is preferable that the pitchof concave and convex patterns on one side is different from the pitchof concave and convex patterns on the other side. If these are equal,the moiré phenomenon tends to take place.

The embossment pattern (concave and convex patterns) in the secondaspect of the invention is not particularly restricted but includeslinear, grid-like, radial and hemispherical, among others.

Since, in the second aspect of the invention, said concave portions onat least one side of the interlayer form a trough-like geometry which iscontinual at the bottom, the bottom of said concave portions iscontinual so that good deaeration can be achieved in preliminary contactbonding.

In addition, since the top of said convex portion forms a plateau, thearea of the top of said convex portion and the volume of said convexportion are increased so that the premature marginal sealing of theglass-interlayer assembly in preliminary contact bonding is effectivelyinhibited. Therefore, the air present in the central part of theglass-interlayer assembly is also effectively purged out. In particular,the above characteristics are further improved when the ratio of thewidth of said plateau at top of said convex portion relative to thepitch of said convex portions is not less than 20%.

The third aspect of the invention is concerned with an interlayer for alaminated glass in which said concave portion on at least one side has atrough-like geometry and segmenting walls are formed in said trough-likegeometry.

In the third aspect of the invention, said trough has segmenting wallstherein. In this arrangement, even if a positive seal cannot be carriedout down to the bottom of the trough, the segmenting walls lying abovethe level of the bottom of necessity help to insure a positive sealbetween the interlayer and the glass sheet, thus allowing milder sealingconditions to be employed.

The height of the above segmenting wall is preferably smaller than thedepth of the trough. If the height of the segmenting wall is greaterthan the depth of the trough, there maybe cases in which deaeration andsealing will be insufficient.

The above segmenting walls are preferably arranged at equal intervals.If the interval of the above segmenting walls is not uniform, it mayhappen that deaeration does not proceed with efficiency.

In the third aspect of the invention, the pitch of the concave andconvex patterns on one side is preferably different from the pitch ofthe concave and convex patterns on the other side. If the pitches aresimilar, the moiré phenomenon is liable to take place.

The fourth aspect of the invention is concerned with an interlayer for alaminated glass in which said concave portion on at least one side has atrough-like geometry and is not on one and the same level, and a ratioof a surface roughness (Rz) and a surface roughness (Rzv) of a negativemodel is Rzv/Rz≧0.25 on at least one side.

Rz, referred to above, represents the surface roughness of theembossments on at least one side and it is a 10-point average roughnessas measured with a conical tracer (tip radius of curvature 5 μm, vertexangle 90°) in accordance with JIS B 0601. Rzv, referred to above,represents the surface roughness of the negative model used for theembossment on at least one side and it is a 10-point average roughnessas measured with a wedge-shaped tracer shown in FIG. 17 (tip width 1000μm, opposite face angle 90°) shifted in a direction normal to the tipwidth in accordance with JIS B 0601.

As used in this specification, the term “not on one and the same level”means that the trough is not uniform in depth.

Rz, referred to above, represents the well-known ordinary 10-pointaverage roughness and is generally measured with a digital tracer-typeelectric surface roughness analyzer.

Rzv, referred to above, is also generally measured with a digitaltracer-type electric surface roughness analyzer.

Stated differently, said Rzv is the 10-point average roughness asmeasured with a wedge-shaped tracer (tip width 1000 μm) assuming thatthe convex portion of the embossment on the sheet surface is a concaveportion and the concave portion of the embossment is a convex portion.Here, the tip width of the wedge-shaped tracer is set to 1000 μm inconsideration of the pitch of the convex portion and concave portion ofthe embossment (which is usually 200 to 1000 μm). By, using a tracerhaving a tip width of 1000 μm, the change in geometry of particularlydeep concave portions among the concave portions of the embossments canbe measured.

The above-mentioned Rzv serves also as a parameter representing thelevel of the concave portion of the embossment and is closely related tothe ease of escape of air in deaeration and the sealing effect. On theother hand, said Rz serves also as a parameter representing thecondition of the convex portion of the embossment and is not onlyrelated to the resistance to movement of air but is closely related tothe ease of collapse of the embossment in laminating work.

Intensive analysis of the relationship of the above Rzv to Rz revealedthat when the relation of Rzv/Rz≧0.25is satisfied, the deaeration andsealing performances in preliminary contact bonding are satisfactoryand, in the final contact bonding carried out under heat and pressure inan autoclave, there is obtained an interlayer almost free of the airbubbles which might be formed between the glass and interlayer due toinfiltration of pressurized air from the poorly sealed positions.

Blocking of the interlayer depends on the number of the interlayerstacked during storage but generally an interlayer having a 10-pointaverage roughness (Rz) value of 20 to 100 μm is employed and for such aninterlayer, it is only necessary to take into consideration a gravity ofthe order of about 500 to 1000 sheets. It has been found that theinterlayer satisfying the above-defined conditions shows satisfactoryblocking resistance under a load of such magnitude and can be easilyhandled in storage and laminating work.

In the fourth aspect of the invention, the preferred interlayer is onehaving a defined surface roughness on both sides thereof but aninterlayer having a defined surface roughness only on one side with theother side having the conventional embossment comprising fine concaveand convex patterns is also acceptable.

In the fourth aspect of the invention, the trough may be provided in alinear configuration or in a grid configuration.

The fifth aspect of the invention is an interlayer for a laminated glassin which the concave portion on at least one side has a continualtrough-like geometry and said convex portion on the same side hassegmenting troughs while a bottom of said segmenting troughs is not onone and the same level as the bottom of the continual trough-likegeometry of said concave portion.

The main function of the segmenting troughs of the convex portion is tocontrol the magnitude of the concave and convex. Thus, when the numberof said segmenting troughs is increased, the volume of the concave andconvex is decreased to facilitate sealing particularly at the marginalpart of the glass-interlayer assembly and conversely when the number ofsaid segmenting troughs is decreased, the volume of surfaceirregularities is increased so that the premature marginal sealing andconsequent entrapment of air in the central region of theglass-interlayer assembly can be effectively precluded.

The geometry of said segmenting trough in the convex portion can befreely controlled so that an interlayer having both a good deaerationcharacteristic due to the continual trough-like geometry of the concaveportion and the good sealing characteristic due-to the above-segmentingtroughs of the convex portion can be provided easily and efficiently inresponse to varied processing needs of various users.

FIG. 18 is a perspective view showing the emboss design of an interlayerfor a laminated glass according to the fifth aspect of the invention andFIG. 19 is a plan view of the same.

In the fifth aspect of the invention, the trough-like geometry 1 of theconcave portion and segmenting troughs 2 of the convex portion may beprovided in a grid or a random configuration but the grid configurationis preferred.

Further in the fifth aspect of the invention, the depth of segmentingtroughs 3 in the convex portion may be uniform or random, although auniform depth is preferred.

In the fifth aspect of the invention, both sides of the interlayerpreferably have an embossment satisfying the herein-defined conditionsbut an interlayer having an embossment satisfying defined conditionsonly on one side with the other side having the conventional embossmentis also acceptable.

In the fifth aspect of the invention, the concave portions on at leastone side have a continual trough-like geometry and even when thegeometry of the embossment is destroyed under heat and pressure in thepreliminary contact bonding of the glass-interlayer assembly, thecontinual trough-like geometry of the concave portion persists to thelast. Therefore, sufficient deaeration can be achieved.

Furthermore, in the fifth aspect of the invention, the convex portioncomplementary to the concave portion has segmenting walls and, moreover,the bottom of the segmenting trough is not on one and the same level asthe bottom of the continual trough-like geometry of the concave portion,the sealing performance in laminated glass processing can be improved bycontrolling the geometry of the segmenting trough of the convex portion.Furthermore, through such control of the geometry of the segmentingtrough of the convex portion, the different processing needs of varioususers can be met with ease and efficiency.

The sixth aspect of the invention is concerned with an interlayer for alaminated glass in which at least one side is provided with concavetroughs, and an angle between said concave trough and a direction ofextrusion of the thermoplastic resin sheet is less than 25°.

If this angle between the concave trough provided on the thermoplasticresin sheet used in sixth aspect of the invention and the extrusiondirection of the thermoplastic sheet is too large, bubbling (formationof air bubbles) tends to occur in the laminated glass particularly whenthe preliminary contact bonding is performed by the draw deaerationmethod and, moreover, if the concave trough extends to the edge of thesheet, a sealing defect occurs to entrap air in the final contactbonding which is carried out under heat and pressure in an autoclave.Therefore, said angle is restricted to less than 25°, preferably lessthan 15°.

The concave trough mentioned above is a continual trough and when aplurality of troughs are present, they are preferably identical indepth, width and pitch, although there may be a moderate undulation atthe bottom of the trough or they may be randomly present, varying indepth, width, and/or pitch. The sectional configuration of the concavetrough is not particularly restricted but each trough may for example beV-shaped, U-shaped, or bracket-shaped.

Regarding the depth of the above concave trough, if the trough is tooshallow, the deaeration performance will be decreased and if it is toodeep, a sealing defect may develop. Therefore, the depth of the troughis preferably 5 to 500 μm, more preferably 20 to 70 μm. The width of thetrough is preferably 20 to 100 μm, for if it is too narrow, thedeaeration performance will be poor and if it is too broad, a sealingdefect tends to develop. The interval (pitch) of concave troughs ispreferably 0.1 to 10 mm, more preferably 0.2 to 1 mm, for if theinterval is too small, the deaeration performance will be poor and if itis too large, a sealing defect tends to develop.

In the sixth aspect of the invention, concave troughs need only beformed on at least one side of a thermoplastic resin sheet. Thus, it isoptional to provide the interlayer with troughs on one side or on bothsides but in order that a sufficient deaeration effect maybe obtained,troughs are preferably formed on both sides.

In the sixth aspect of the invention, the thermoplastic resin sheet isformed not only with concave troughs but also with a multiplicity offine depressions and convex portions as embossed on both sides. Thedistribution of these fine concave and convex may be orderly or notorderly. Moreover, the depth and height of concave and convex may eachbe uniform throughout or varying.

In the sixth aspect of the invention which has the above constitution,concave troughs persist even after the concave and convex of theembossment are abolished by heat and pressure in preliminary contactbonding, particularly in the draw deaeration process in processinglaminated glass. Therefore, sufficient deaeration can be insured.

When the draw deaeration method is used in preliminary contact bonding,the ease of escape of air in this preliminary contact bonding stage isclosely and substantially exclusively related to the proportion ofconcave troughs relative to the total depression portion and theflatness and smoothness of the concave troughs, with the pitch andarrangement of convex portions being not so influential factors.

In the sixth aspect of the invention, by virtue of the formation ofconcave troughs in parallel with the extrusion direction, a route forair can be insured even when, for example, the convex portion is in theform of a mountain ridge, the deaeration passageway is arranged in agrid form, and deaeration is performed at right angles with the mountainridge. Therefore, even when the deaeration is carried out at rightangles with said mountain ridge, the air will not be dammed and, hence,no air pool will be formed.

Furthermore, in the recent technology for laminated glass production, itis the rule rather than exception to construct a glass-interlayerassembly along the winding flow direction of the interlayer (generallythe extrusion direction of the thermoplastic resin sheet) and carryingout a draw deaeration along the winding flow direction. Therefore, themarginal sealability of the interlayer in preliminary contact bonding isimproved when concave troughs are oriented along the winding flowdirection of the interlayer.

Furthermore, when a glass-interlayer assembly is subjected topreliminary contact bonding, many processing manufactures generally setthe initial speed at insertion of the assembly into the multiroll systemand the speed immediately before takeoff at definitely slower levelscompared with the normal speed for the purpose of preventing cracking ofglass due to curving, with the result that the leading end and trailingend of the laminate can be sufficiently sealed even if the roughness ofthe embossment and the size of the concave trough at these ends arelarge. There is no problem with sealing at the lateral edges unless aconcave trough exists at the lateral edge of the assembly.

The seventh aspect of the invention is concerned with an interlayer fora laminated glass in which concave portion on at least one side has atrough-like geometry, and said trough-like geometry is constant insectional area while has a depth distribution of troughs having a depthof not less than 5% of the maximum trough depth.

In the seventh aspect of the invention, the concave portion on at leastone side has the trough-like geometry and, with the depth of the troughbeing reduced locally, has a depth distribution of troughs having adepth of not less than 5% of the maximum trough depth, while thesectional area of the trough-like geometry is kept constant. Therefore,in the deaeration by the vacuum deaeration technique, an effective routefor air is insured at initiation of deaeration and the shallow partsbecome more ready to adhere to the glass so that the sealability isimproved.

Troughs having a depth distribution of not less than 5% of the maximumtrough depth as mentioned above are preferably provided at an interval(pitch) of not more than 10 mm. If this pitch exceeds 10 mm, the troubleof bubble formation in the marginal part of the glass-interlayerassembly may occur in the course of deaeration. The more preferred pitchis not more than 2 mm.

In the seventh aspect of the invention, the trough-like geometry ispreferably provided in the direction of flow of the interlayer. As usedin this specification, the “flow direction” means the direction oftravel of the glass-interlayer assembly on a laminated glass productionline. In this arrangement, not only the molding of the roll to be usedfor transfer of the trough-like geometry to the interlayer but also thetransfer to the substrate interlayer sheet is facilitated. In addition,this arrangement is preferred in view of the fact that the direction ofdeaeration in the draw deaeration technique is the flow direction of theinterlayer.

The above trough-like geometry need only be formed on one side of theinterlayer in accordance with the seventh aspect of the invention but ispreferably present on both sides. When the trough-like geometry ispresent on at least one side of the interlayer of the invention, theformation of air bubbles can be prevented by using the interlayer of theinvention when, for example, the inner side of the glass has adistribution of roughness or the interlayer is to be used only on theside for absorbing the steps due to black ceramics printing or the like.

The interlayer according to the seventh aspect of the invention can beused with advantage when the deaeration is performed by the vacuumdeaeration technique but by increasing the fineness of the trough, forexample by reducing the depth of the trough to less than about 30 μm, itcan be used with success when the deaeration is performed by the drawdeaeration technique as well.

The technology of creating said trough-like geometry includes, forexample, the method which comprises processing the surface of a metalroll or a flat plate (pressed plate) into a convex (ridge-like) form andtransfer the form to a substrate interlayer.

Referring, further, to the above trough-like geometry, the depth of thetrough can be varied with its sectional area kept constant by indentingthe surface ridge of a metal roll or flat plate (pressed plate) locallyand particularly the method which comprises biasing a mill having adefined geometry against said surface to vary the depth of the trough ispreferred in that the sectional area of the trough can be easily keptconstant. In contrast, if the surface ridge of a metal roll or flatplate (pressed plate) is machined with a bit or the like to reduce itsheight, the sectional area of that portion will be decreased.

The interlayer according to the present invention is used for themanufacture of laminated glass products. Such a laminated glass can beobtained by interposing the interlayer of the invention between at leastone pair of glass sheets and consolidating the assembly into an integralunit.

The glass sheet mentioned above is not particularly restricted butincludes inorganic glass sheets; and organic glass sheets such as thepolycarbonate sheet, polymethyl methacrylate sheet, and so forth.

The structure of said laminated glass need only be such that theinterlayer of the invention is interposed between two glass sheets andis otherwise not particularly restricted. Thus, the structure is notrestricted to the 3-layer structure of sheet glass/interlayer/sheetglass but may be a multilayer structure of, for example, sheetglass/interlayer/sheet glass/interlayer/sheet glass.

The technology of manufacturing a laminated glass product using theinterlayer of the invention is not particularly restricted. Thus, thedesired laminated glass can be obtained by the same productiontechnology as used in the manufacture of the conventional laminatedglass, for example by interposing the interlayer between at least onepair of glass sheets, subjecting the whole to preliminary contactbonding for deaeration and provisional adhesion, and subjecting it tofinal contact bonding, for example, in an autoclave.

When the laminated glass is to be manufactured using the interlayer madeof, for example, a plasticized polyvinyl butyral resin sheet inaccordance with the invention, the preliminary contact bonding and finalcontact bonding can for example be carried out in accordance with thefollowing procedures.

The preliminary contact bonding procedure may comprise interposing theinterlayer between two transparent inorganic glass sheets and passingthe assembly over a nip roll for preliminary contact bonding withconcurrent deaeration for example at a pressure of 2 to 1000 kPa and atemperature of 50 to 100° C. (draw deaeration technique) oraccommodating said assembly in a rubber bag, connecting the bag to avacuum system, and evacuating the bag to a vacuum of −40 to −75 kPa(absolute pressure 36 to 1 kPa) while increasing the temperature forpreliminary contact bonding at 60 to 100° C. (vacuum deaerationtechnique).

The assembly subjected to the preliminary contact bonding procedure isfurther subjected to final contact bonding in an autoclave in theconventional manner or by means of a press set to a temperature of 120to 150° C. under a pressure of 200 to 1500 kPa to give the laminatedglass.

The laminated glass thus manufactured also constitutes one aspect of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The following examples illustrate the present invention in furtherdetail without defining the scope of the invention.

EXAMPLE 1

To 100 parts by weight of polyvinyl butyral resin (average degree ofpolymerization 1700, residual acetyl group 1 mol %, butyralizationdegree 65 mol %) was added 40 parts by weight of the plasticizertriethylene glycol-di-2-ethylbutyrate, and using an extruder, theresulting mixture was melt-kneaded and extruded in a sheet form from theextrusion die to give a 0.76 mm-thick polyvinyl butyral resin sheet (PVBsheet).

An engraving mill (mother mill) having a linear embossment design(concave and convex patterns) for embossing use was forced against thesurface of one of a pair of metal embossing rolls and this metal rolland the engraving roll were driven in association to transfer theembossment design of the engraving mill to the metal roll. Then, theengraving mill was shifted in the axial direction of the metal roll insteps of the unit embossment design to transfer the embossment design ofthe engraving mill to the metal roll in the same manner as above toconstruct an embossing roll having an orderly array of linear embossmentdesigns. The embossment pitch of the engraving mill was 250 μm.

An engraving mill (mother mill) having a linear embossment design wasforced against the surface of the other metal roll of said pair ofembossing rolls and the metal roll and the engraving mill were driven inassociation to transfer the embossment design of the engraving mill tothe metal roll. Then, the engraving mill was shifted in the axialdirection of the metal roll in steps of the unit embossment design totransfer the embossment design of the engraving mill serially to themetal roll in the same manner as the above to construct an embossingroll with an orderly array of linear embossment designs. The pitch ofthe emboss design of said engraving mill was 320 μm.

The PVB sheet (0.76 mm thick) obtained as above was passed over theembossing roll pair obtained as above to manufacture an interlayer sheetfor laminated glass having an orderly array of linear embossment designson both sides but varying in the pitch of designs from one side to theother side.

EXAMPLE 2

Except that the pitch of the embossment of one engraving mill (mothermill) was changed to 300 μm and the pitch of the embossment of the otherengraving mill (mother mill) was changed to 375 μm, the procedure ofExample 1 was repeated to manufacture an interlayer for a laminatedglass having an orderly array of linear embossments on both sides andvarying in the pitch of embossments from one side to the other side.

EXAMPLE 3

Except that the pitch of the embossments of one engraving mill (mothermill) was changed to 300 μm and the pitch of the embossments of theother engraving mill (mother mill) was changed to 430 m, the procedureof Example 1 was repeated to manufacture an interlayer for a laminatedglass having an orderly array of linear embossments on both sides andvarying in the pitch of embossments from one side to the other side.

The face side, reverse side, and cross-section views of the embossmentdesigns (concave and convex patterns) of the interlayers for laminatedglass as obtained in Examples 1 to 3 are schematically illustrated inFIG. 1.

COMPARATIVE EXAMPLE 1

Except that the pitch of the embossments was set to 300 μm for bothengraving mills (mother mills), the procedure of Example 1 was repeatedto manufacture an interlayer for a laminated glass having an orderlyarray of linear embossments on both sides with the same pitch ofembossments for both sides.

The face side, reverse side and cross-section views of the embossmentdesign (concave and convex patterns) of the interlayer for a laminatedglass as obtained in Comparative Example 1 are schematically shown inFIG. 2.

EXAMPLE 4

To 100 parts by weight of polyvinyl butyral resin (average degree ofpolymerization 1700, residual acetyl group 1 mol %, butyralizationdegree 65 mol %) was added 40 parts by weight of the plasticizertriethylene glycol-di-2-ethylbutyrate (3 GH), and, using an extruder,the resulting mixture was melt-kneaded and extruded in a sheet form fromthe extrusion die to give a 0.76 mm-thick polyvinyl butyral resin sheet(PVB sheet).

An engraving mill (mother mill) having a hemispherical embossment designwas forced against the surface of one of a pair of metal embossing rollsand this metal roll and the engraving mill were driven in association totransfer the embossment design of the engraving mill to the metal roll.Then, the engraving mill was shifted in the axial direction of the metalroll in steps of the unit embossment design to transfer the embossmentdesign of the engraving mill to the metal roll in the same manner asabove to construct an embossing roll having an orderly array ofhemispherical embossments. The pitch of the embossments of the engravingmill was 200 μm.

An engraving mill (mother mill) having a hemispherical embossment designwas forced against the surface of the other metal roll of said pair ofembossing rolls and the metal roll and the engraving mill were driven inassociation to transfer the embossment design of the engraving mill tothe metal roll. Then, the engraving mill was shifted in the axialdirection of the metal roll in steps of the unit embossment design totransfer the embossment design of the engraving mill serially to themetal roll to construct an embossing roll having an orderly array ofhemispherical embossments. The pitch of embossments of said engravingmill was 300 μm.

The PVB sheet (0.76 mm thick) obtained as above was passed over theembossing roll pair obtained as above to manufacture an interlayer for alaminated glass having an orderly array of hemispherical embossments onboth sides but varying in the pitch of embossments from one side to theother side. The face side, reverse side and cross-section views of theembossment pattern of the interlayer thus obtained are shown in FIG. 3.

EXAMPLE 5

Except that a linear embossment design was used for engraving mills(mother mills) and the pitch of embossments of one of the engravingmills was set to 250 μm and that of the other engraving mill to 300 μm,the procedure of Example 4 was otherwise repeated to manufacture aninterlayer for a laminated glass having a linear embossment pattern onboth sides and varying in the pitch of embossments from one side to theother side. The face side, reverse side, and cross-section views of theembossment design of the interlayer thus obtained are shown in FIG. 4.

EXAMPLE 6

Except that a grid embossment design was used for engraving mills(mother mills) and the pitch of embossments of one of the engravingmills was set to 200 μm and that of the other engraving mill to 400 μm,the procedure of Example 4 was otherwise repeated to manufacture aninterlayer for a laminated glass having a grid pattern of embossments oneither side and varying in the pitch of embossments from one side to theother side. The face side, reverse side, and cross-section views of theembossment design of the interlayer thus obtained are shown in FIG. 5.

EXAMPLE 7

Except that a linear embossment design with a pitch of 220 μm was usedfor one of the engraving mills (mother mills) and the grid embossmentdesign with a pitch of 320 μm was used for the other engraving mill, theprocedure of Example 4 was otherwise repeated to manufacture aninterlayer for a laminated glass having an orderly array of linearembossments on one side and an orderly array of grid embossments on theother side and varying in the pitch of embossments from one side to theother.

COMPARATIVE EXAMPLE 2

Except that a linear embossment design with a pitch of 210 μm was usedfor both engraving mills (mother mills), the procedure of Example 4 wasotherwise repeated to manufacture an interlayer for a laminated glasshaving an orderly linear embossment pattern on both sides at the samepitch of embossments for both sides. The face side, reverse side, andcross-section views of the embossment design of the interlayer thusobtained are shown in FIG. 6.

Using the 9 kinds of interlayers obtained in Examples 1 to 7 andComparative Examples 1 and 2, respectively, the average surfaceroughness (Rz) and average pitch (Sm) of embossments on each side weremeasured by the following methods. The results are shown in Table 1 andTable 2.

(Measurement of Rz)

Using a digital tracer system electric surface roughness analyzer (tradename “SE-2000”, manufactured by Kosaka Kenkyusho) and a conical tracer(tip radius of curvature 5 μm, vertex angle 90 degrees), the 10-pointaverage surface roughness {Rz (μm)} of the embossment design on eachside of the interlayer was measured in accordance with JIS B0601.

(Measurement of Sm)

Under the microscope, the average pitch {Sm (μm)} of embosses on eachside of the interlayer was measured.

Furthermore, with each of said 9 kinds of interlayers, the appearance ofthe moiré phenomenon was evaluated by the following method. The resultsare shown in Table 1 and Table 2.

(Appearance of the Moiré Phenomenon)

The interlayer was moved slowly and continuously and the appearance ofthe moiré phenomenon was visually monitored.

Then, using each of said 9 kinds of interlayers, preliminary contactbonding was carried out by the following two alternative methods (drawdeaeration and vacuum deaeration), followed by final contact bonding tofabricate 9 kinds of laminated glass sheets.

(a) Draw Deaeration

The interlayer was sandwiched between two sheets of transparent floatglass (30 cm long×30 cm wide×3 mm thick) and the superfluous part wastrimmed off. The resulting assembly was heated in an oven to an articletemperature (preliminary contact bonding temperature) of 60° C., 70° C.or 80° C. and passed over a nip roll (air cylinder pressure 350 kPa,linear velocity 10 m/min) for preliminary contact bonding.

(b) Vacuum Deaeration

The interlayer was sandwiched between two sheets of transparent floatglass (30 cm long×30 cm wide×3 mm thick) and the superfluous part wastrimmed off. The resulting assembly was transferred into a rubber bagand, with the rubber bag connected to a suction system, heated byexternal heating while maintaining at a negative pressure of −60 kPa(absolute pressure 16 kPa) for 10 minutes. After the assembly had beenheated to an article temperature (preliminary contact bondingtemperature) of 60° C., 80° C. or 100° C., the pressure was returned toatmospheric pressure to complete preliminary contact bonding.

The assembly subjected to preliminary contact bonding by the abovemethod (a) or (b) was held in an autoclave at a temperature of 140° C.and a pressure of 1.3 MPa for 10 minutes, at the end of which time thetemperature was lowered to 50° C. and the pressure was returned toatmospheric pressure to complete the final contact bonding and provide alaminated glass.

The 9 kinds of laminated glass obtained as above were subjected to abake test according to the following protocol and the deaerationperformance of preliminary contact bonding was evaluated. The resultsare shown in Table 1 and Table 2.

(Bake Test of Laminated Glass)

The laminated glass was heated in an oven at 140° C. for 2 hours. Then,the glass was taken out of the oven, allowed to cool over 3 hours, andwas visually inspected to count the number of sheets with air bubblesand evaluate the deaeration performance. The number of sheets tested was100 for each glass product. The fewer the number of glass sheets withair bubbles is, the superior is the deaeration and sealing performance.

TABLE 1 Example 1 Example 2 Example 3 Compar. Ex. Embossment Embossmentdesign Linear Linear Linear Linear of interlayer Embossment arrangementOrderly Orderly Orderly Orderly Face Average surface roughness: Rz (μm)36.2 43.2 44.5 40.6 side Average pitch: Sm (μm) 252.0 302.2 303.0 305.0Reverse Average surface roughness: Rz (μm) 42.5 43.0 39.4 41.2 sideAverage pitch: Sm (μm) 324.0 372.5 431.2 305.0 Incidence of moiré No NoNo Yes Preliminary contact Draw deaeration 60 70 80 60 70 80 60 70 80 6070 80 bonding temperature (° C.) Vacuum deaeration 60 80 100 60 80 10060 80 100 60 80 100 Bake test of laminated glass Draw deaeration 0 1 0 20 0 0 1 0 0 2 0 (the number of sheets with air Vacuum deaeration 1 0 0 00 0 1 0 1 1 0 0 bubbles/100 sheets)

TABLE 2 Example 4 Example 5 Example 6 Example 7 Compar. Ex. 2 EmbossmentEmbossment design Face side Hemispherical Linear Grid Linear Linear ofinterlayer Reverse side Hemispherical Linear Grid Grid Linear Embossmentarrangement Orderly Orderly Orderly Orderly Orderly Average surface Faceside 36.2 43.2 44.5 42.5 40.6 roughness: Rz (μm) Reverse side 42.5 43.039.4 40.6 41.2 Average pitch: Face side 210.0 255.2 213.0 220.4 215.0 Sm(μm) Reverse side 310.0 302.5 421.2 320.2 210.2 Incidence of moiré No NoNo No Yes Preliminary contact Draw 60 70 80 60 70 80 60 70 80 60 70 8060 70 80 bonding temperature (° C.) deaeration Vacuum 60 80 100 60 80100 60 80 100 60 80 100 60 80 100 deaeration Bake test of laminatedglass Draw 0 1 0 2 0 0 0 1 0 0 1 1 0 2 0 (the number of sheets with airdeaeration bubbles/100 sheets) Vacuum 1 0 0 0 0 0 1 0 1 2 0 0 1 0 0deaeration

It is apparent from Tables 1 and 2 that the interlayers for laminatedglass according to Examples 1 to 7 of the invention were invariably freeof the moiré phenomenon. This result indicates good work ability incutting and laminating operations. Furthermore, the laminated glassproducts using the above interlayers according to Examples 1 to 7invariably showed few sheets with air bubbles (rejects) in the baketest, regardless of the preliminary contact bonding temperature used inthe draw deaeration process or the vacuum deaeration processes. Theseresults indicate an invariably satisfactory deaeration performance inpreliminary contact bonding.

In contrast, the interlayer for a laminated glass according toComparative Example 1 as manufactured using a pair of embossing rollsfabricated from two engraving mills (mother mills) with the same pitchof embossments (300 μm) and the interlayer for a laminated glassaccording to Comparative Example 2 as manufactured by using a pair ofembossing rolls fabricated from two engraving mills (mother mills) withthe same embossment design (linear) and pitch were both good indeaeration performance at preliminary contact bonding but developed themoiré phenomenon. These results are indicative of poor workability incutting and laminating operations.

EXAMPLE 8

As the thermoplastic resin sheet, “DXN film” (polyvinyl butyral resinsheet, product of Sekisui Chemical) was used.

A pair of rolls, namely a metal roll subjected to surface milling with atriangular oblique line type mill (product of Yuri Roll Co.) and arubber roll having a JIS hardness of 45 to 75, was used as the surfaceirregularity transfer device and said DXD film was passed over thissurface irregularity transfer device to apply an embossed depressionforming a trough design with a continual bottom on one side of the DXNfilm. The transfer conditions used were as follows.

-   Temperature of DXN film: room temperature-   Roll temperature: 130° C.-   Linear velocity: 10 m/min.-   Press linear pressure: 500 kPa

Then, the other side of the DXN film was also subjected to the abovetreatment to give an interlayer having an orderly linear patterncomprising concave portions with a trough-like configuration continualat the bottom and convex portions each having a plateau-forming top onboth sides. The interval (pitch) of the embossed convex portions of theinterlayer was 300 μm, the width of the plateau-forming top of theembossed convex portion was 250 μm, and the width of the embossedconcave portion was 50 μm.

EXAMPLE 9

Except that the pitch of the embossed convex portions was set to 300 μm,the width of the plateau-forming top of the embossed convex portion wasset to 160 μm, and the width of the embossed concave portion was set to140 μm, the procedure of Example 8 was otherwise repeated to give aninterlayer having an orderly linear pattern comprising embossed concaveportions having a trough-like configuration continual at the bottom andembossed convex portions each having a plateau-forming top on bothsides.

The embossment design (concave and convex patterns) of the interlayersobtained in Example 8 and Example 9 is schematically depicted in FIG. 7.

EXAMPLE 10

Except that the interval (pitch) of the embossed convex portions was setto 200 μm, the width of the plateau-forming top of the embossed convexportion-was set to 50 μm, the width of the embossed concave portion wasset to 150 μm, and a grid configuration was selected for the embossmentdesign, the procedure of Example 8 was otherwise repeated to give aninterlayer having an orderly grid embossment pattern comprising embossedconcave portions having a trough-like configuration continual at thebottom and embossed convex portions each having a plateau-formingconfiguration on both sides.

EXAMPLE 11

Except that the interval (pitch) of the embossed convex portions was setto 500 μm, the width of the plateau-forming top of the embossed convexportion was set to 400 μm, the width of the embossed concave portion wasset to 100 μm, and a grid configuration was selected for the embossdesign, the procedure of Example 8 was otherwise repeated to give aninterlayer having an orderly grid embossment pattern comprising embossedconcave portions having a trough-like geometry continual at the bottomand embossed convex portions each having a plateau-forming top on bothsides.

The embossment design (concave and convex patterns) of the interlayersobtained in Example 10 and Example 11 is schematically depicted in FIG.8.

COMPARATIVE EXAMPLE 3

Except that the top of the embossed convex portion was not made aplateau and the pitch of embossed convex portions and the width of theembossed concave portion were set to 200 μm, the procedure of Example 8was otherwise repeated to give an interlayer having an orderly linearemboss pattern comprising embossed concave portions having a trough-likegeometry continual at the bottom and embossed convex portions with topsnot forming a plateau on both sides. The embossment pattern (concave andconvex patterns) of the interlayer obtained in this Comparative Exampleis schematically depicted in FIG. 9.

With the 5 kinds of interlayers obtained in Examples 8 to 11 andcomparative Example 3, the average surface roughness (Rz) of theembossment was measured by the same method as in Example 1. The resultsare shown in Table 3.

Using each of the above 5 kinds of interlayers, the preliminary contactbonding by the vacuum deaeration method and the final contact bondingwere serially carried out in the following manner to construct 5 kindsof laminated glass products.

(Vacuum Deaeration)

The interlayer was sandwiched between two transparent float glass sheets(30 cm long×30 cm wide×30 cm thick) and the superfluous part was trimmedoff to fabricate a glass-interlayer assembly. The assembly wastransferred into a rubber bag. The rubber bag was connected to a vacuumsuction system and heated externally and held at a negative pressure of−60 kPa (absolute pressure 16 kPa) for 10 minutes. The heating wasperformed until the temperature of the assembly (preliminary contactbonding temperature) had reached 70° C. And the pressure was thenreturned to atmospheric pressure to complete preliminary contactbonding. The three different deaeration start temperatures of 40° C.,50° C. And 60° C. Were used at preliminary contact bonding.

(Final Contact Bonding)

The glass assembly subjected to preliminary contact bonding in the abovemanner was placed in an autoclave and held at a temperature of 140° C.and a pressure of 1300 kPa for 10 minutes. The temperature was thenlowered to 50° C. And the pressure was returned to atmospheric pressureto complete final contact bonding and give a laminated glass.

The 5 kinds of laminated glass sheets obtained as above wererespectively subjected to a bake test in the same manner as in Example 1to evaluate the deaeration performance at preliminary contact bonding.The results are shown in Table 3.

TABLE 3 Compar. Example 8 Example 9 Example 10 Example 11 Ex. 3Embossment Embossment design Linear Linear Grid Grid Linear ofinterlayer Embossment arrangement (distribution) Orderly Orderly OrderlyOrderly Orderly Embossment Pitch of convex portions 300 300 200 500 200geometry (a: μm) Width of flat part of convex portions 250 160 50 400 —(b: μm) b/a (%) 83.3 53.3 25.0 80.0 — Width of concave portions (c: μm)50 140 150 100 200 Average surface roughness 42.5 40.5 45.2 41.2 60.2(Rz: μm) Results of Condtions of Initial vacuum temperature (° C.) 40 5060 40 50 60 40 50 60 40 50 60 40 50 60 evaluation vacuum Preliminarycontact 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 deaeration bondingtemperature (° C.) Bake test of laminated glass 0 0 1 0 1 5 1 5 10 1 0 110 50 90 the number of sheets with air bubbles/100 sheets)

It is apparent from Table 3 that the laminated glass sheets manufacturedby using the interlayers according to Examples 8 toll of the inventionshowed few sheets with air bubbles (rejects) in the bake test invariablyat the deaeration start temperatures of 40° C., 50° C. And 60° C. in thepreliminary contact bonding by the vacuum deaeration method. The resultindicates that good deaeration was obtained even without criticalcontrol of deaeration start temperature in preliminary contact bondingand even at the ordinary preliminary contact bonding temperature (70°C.), not a deliberately increased preliminary contact bondingtemperature.

In contrast, the laminated glass manufactured by using the interlayer ofComparative Example 3 where the top of the embossed convex portion wasnot flattened to a plateau gave quite many sheets with air bubbles(rejects) in the bake test when the deaeration start temperature inpreliminary contact bonding was 50° C. or higher. This result indicatesthat unless the deaeration start temperature in preliminary contactbonding is strictly controlled to at least below 50° C., the prematuresealing takes place around the edge of the glass-interlayer assembly tointerfere with a thorough removal of air in the central part of theassembly.

EXAMPLES 12 TO 16

(Preparation of the Interlayer for a Laminated Glass)

For embossing, a variety of embossing rolls were provided. As thethermoplastic resin sheets, DXN films (polyvinyl butyral resin sheet,product of Seisui Chemical) was provided. The Ra values of the DXN filmsused in Examples 12 to 16 are shown in Table 4.

Using a pair of rolls, namely an embossing roll and a rubber roll, asthe surface irregularity transfer device, the above DXN film was passedover this surface irregularity transfer device to give an interlayer fora laminated glass having an embossment pattern on both sides. Thetransfer conditions used are as follows.

-   Temperature of DXN film: room temperature-   Roll temperature: 130° C.-   Linear velocity: 10 m/min-   Press linear pressure: 500 kPa

The embossment patterns (concave and convex patterns) of the interlayersfor laminated glass as obtained in Examples 12 to 16 are shown in Table4.

FIG. 10 shows the embossment pattern (concave and convex patterns) ofthe interlayers for laminated glass as obtained in Example 12 andExample 13; FIG. 11 shows the embossment pattern (concave and convexpatterns) of the interlayers for laminated glass as obtained in Example14 and Example 15; and FIG. 12 shows the embossment pattern (concave andconvex patterns) of the interlayer for a laminated glass as obtained inExample 16.

COMPARATIVE EXAMPLE 4

(Production of the Interlayer for a Laminated Glass)

Except that the routinely extruded non-embossed sheet (polyvinyl butyralresin sheet) was used as the thermoplastic resin sheet, the procedure ofExamples was otherwise repeated to give an interlayer for a laminatedglass having an embossment pattern on both sides.

The embossment pattern (concave and convex patterns) of the interlayerfor a laminated glass as obtained in Comparative Example 4 is shown inTable 4.

FIG. 13 is a schematic representation of the embossment pattern (concaveand convex patterns) of the interlayer for a laminated glass as obtainedin Comparative Example 4.

For each of the six kinds of interlayers for laminated glass as obtainedin Examples and Comparative Example, the average surface roughness (Ra)of the embossment was measured by the method described below and theaverage surface roughness (Rz) was measured as in Example 1 for theevaluation of handling workability and self-adhesiveness of theinterlayer. The results are shown in Table 4.

(Measurement of Ra)

Using a digital tracer-type electric surface roughness analyzer (tradename SE-2000, product of Kosaka Kenkyusho) with a wedge-shaped tracer(tip width 1000 μm, facial angle 90°), the 10-point average surfaceroughness {Ra (μm)} of the emboss on each side of the interlayer for alaminated glass was measured in accordance with JIS B 0601.

Moreover, using each of the above six kinds of interlayers for laminatedglass, preliminary contact bonding by the vacuum deaeration techniqueand final contact bonding were carried out serially as in Example 8 tomanufacture six kinds of laminated glass.

These six kinds of laminated glass were respectively subjected to a baketest under the same conditions as in Example 1 to evaluate thedeaeration performance in preliminary contact bonding. The results areshown in Table 4.

TABLE 4 Example Compar. Ex. 12 13 14 15 16 4 Embossment Embossmentdesign Linear Linear Linear Linear Linear Linear of interlayerEmbossment distribution Orderly, Orderly, Orderly, Orderly, Orderly,Orderly, parallel parallel parallel parallel rotated parallel through90° Embossment Pitch of main convex 300 500 300 500 200 200 geometryportions (a: μm) Width of flat part of main 250 400 250 400 100 25convex portions (b: μm) b/a (%) 83 83 80 83 50 12.5 Width of mainconcave 50 100 50 100 100 175 portions (c: μm) Average surfaceroughness, 42.5 40.5 45.2 41.2 50.2 55.6 5 μm tracer (Rz: μm) Averagesurface roughness, 4.1 3.5 2.7 2.0 2.0 0.5 1000 μm Tracer (Ra: μm)Results of Self-adhesive strength (g/15 cm) 350 420 570 980 650 2540evaluation Condtions of Initial vacuum temperature (° C.) 40 50 60 40 5060 40 50 60 40 50 60 40 50 60 40 50 60 vacuum Preliminary contact 70 7070 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70 deaeration bondingtemperature (° C.) Bake test of laminated glass (the number 0 0 1 0 1 21 1 2 2 2 4 3 4 5 4 10 20 or sheets with air bubbles/100 sheets)

It is apparent from Table 4 that the laminated glass sheets manufacturedin the above Examples showed fewer sheets with air bubbles (rejects) dueto bubbling in the bake test when the deaeration start temperature inpreliminary contact bonding by the vacuum deaeration technique was anyof 40° C., 50° C., and 60° C. This result indicates that good deaerationwas obtained even when the deaeration temperature was not criticallycontrolled or even when preliminary contact bonding was carried out atan ordinary preliminary contact bonding temperature (70° C.) withoutusing a deliberately raised preliminary contact bonding temperature.Furthermore, the interlayers for laminated glass according to Examples15 and 16 where the Ra of the plateau of the convex portion was lessthan 2.5 μm showed slightly higher self-adhesiveness than theinterlayers for laminated glass according to Examples 12 to 14 but wasof the order which does not matter from practical points of view.

On the other hand, the interlayer for a laminated glass having no fineirregularities according to Comparative Example in which the ratio (b/a)of the width of the plateau to the pitch of convex portions was lessthan 20% showed exceedingly high self-adhesiveness as compared with theinterlayer for a laminated glass according to the above Examples and thelaminated glass manufactured by using this interlayer for a laminatedglass showed many sheets with air bubbles (rejects) owing to bubbling inthe bake test as compared with the Examples when the deaeration starttemperature in preliminary contact bonding was 50° C. or higher. Thisresult indicates that unless the deaeration start temperature forpreliminary contact bonding is strictly controlled to at least below 50°C., the premature marginal sealing of the glass-interlayer assemblytakes place so that the air present in the central part of the assemblyis not sufficiently removed.

EXAMPLES 17 TO 20 AND COMPARATIVE EXAMPLE 5

For producing various embossment patterns, a variety of embossing rollswere prepared.

A longitudinal pattern-engraving mill (mother mill) was pressed againstone metal roll of a pair of embossing rolls and the metal roll and theengraving mill were driven in association to transfer the concave andconvex patterns of the engraving mill to the metal roll. Then, theengraving mill was shifted serially in the axial direction of the metalroll in steps of the unit design of the concave and convex patterns toconstruct an embossing roll carrying an orderly array of longitudinallinear patterns. Further, in Example 19 and Example 20, a transversepattern-engraving mill was used to transfer the transverse design tosaid metal roll under a load corresponding to 1/10 of the transferpressure of said longitudinal-pattern engraving mill. In this procedure,the arrangement and size of the respective patterns were monitored underthe microscope.

As the thermoplastic resin sheet, “DXN film” (polyvinyl butyral resinsheet, product of Sekisui Chemical) was used.

The above embossing roll was paired with a rubber roll and with theembossing roll controlled at 130° C., the above thermosetting resinsheet was passed over the roll set to apply the predetermined embosspattern.

The embossed pattern formed on the interlayers for laminated glass asobtained in Example 17 and Example 18 is illustrated in FIG. 14; theembossed pattern formed on the interlayers for laminated glass asobtained in Example 19 and Example 20 is illustrated in FIG. 15; and theembossed pattern formed on the interlayer for a laminated glass asobtained in Comparative Example 5 is illustrated in FIG. 16. The pitchof convex portions, depth of troughs, pitch of segmenting walls, andheight of the segmenting wall of each embossment are shown in Table 5.

For each of the 5 kinds of interlayers obtained in Examples 17 to 20 andComparative Example 5, the average surface roughness (Rz) of theembossment was measured by the same method as used in Example 1. Theresults are shown in Table 5.

Moreover, using each of the above 5 kinds of interlayers, preliminarycontact bonding by the vacuum deaeration technique and final contactbonding were serially performed as described below to manufacture 5kinds of laminated glass sheets.

[Vacuum Deaeration Method]

The interlayer was sandwiched between two transparent sheets oftransparent float glass (30 cm long×30 cm wide×3 mm thick) and thesuperfluous part was trimmed off. The resulting glass-interlayerassembly was transferred into a rubber bag and the rubber bag wasconnected to a vacuum suction system. The bag was heated externallyunder a negative pressure of −60 kPa (absolute pressure 16 kPa) for 10minutes, whereby the temperature of the glass-interlayer assembly(preliminary contact bonding temperature) was brought to a predeterminedtemperature. The negative pressure was then returned to atmosphericpressure to complete preliminary contact bonding. The deaeration starttemperature for the above preliminary contact bonding was set to 50° C.And the preliminary contact bonding temperature was set to one of thethree levels, 60° C., 65° C., or 70° C.

(Final Contact Bonding)

The glass-interlayer assembly provisionally bonded by the aboveprocedure was placed in an autoclave and held at a temperature of 140°C. And a pressure of 1300 kPa for 10 minutes. Then, the temperature waslowered to 50° C. And the pressure was returned to atmospheric-pressureto complete final contact bonding and thereby provide a laminated glass.

The resulting 5 kinds of laminated glass sheets were respectivelysubjected to a bake test according to the same protocol as used inExample 1 to evaluate the deaeration performance in preliminary contactbonding. The results are shown in Table 5.

TABLE 5 Example Compar. Ex. 17 18 19 20 5 Embossment Embossment designLinear Linear Grid Grid Linear of interlayer Embossment arrangementOrderly Orderly Orderly Orderly Orderly Embossment Pitch of convexportions (μm) 350 500 350 500 350 geometry Depth of concave portions(μm) 50 50 50 50 50 Pitch of segmenting walls (μm) 500 500 1000 1000 —Height of segmenting walls (μm) 25 25 25 25 — Average surface roughness(Rz: μm) 45.5 43.6 44.5 42.7 44.2 Results of Condtions of Initial vacuumtemperature (° C.) 50 50 50 50 50 evaluation vacuum Preliminary contact60 65 70 60 65 70 60 65 70 60 65 70 60 65 70 deaeration bondingtemperature (° C.) Bake test of laminated glass 5 4 1 2 2 1 4 3 2 5 3 230 15 5 (the number of sheets with air bubbles/100 sheets)

EXAMPLE 21

The surface of a metal roll was machined with an engraving mill (alinear triangular oblique line cup mill) to form concave and convexpatterns (orderly) comprising a multiplicity of concave troughs (linear)triangular in section and the corresponding multiplicity of convexridges (linear). Further, using glass beads (#46), the roll was blastedfrom-a distance of about 30 cm at an air pressure of 100 kPa tofabricate an embossing roll.

On the other hand, 100 parts by weight of polyvinyl butyral resin(average degree of polymerization 1700, residual acetyl group 1 mol %,butyralization degree 65 mol %) was blended with 40 parts by weight ofthe plasticizer triethylene glycol di-2-ethylbutyrate and 0.2 part byweight of the bond strength modulator magnesium acetate, and using anextruder, the resulting mixture was melt-kneaded and extruded from a diein a sheet form to give a 0.76 mm-thick polyvinyl butyral sheet.

Using a pair of embossing rolls fabricated in the above manner and theabove polyvinyl butyral sheet, an interlayer was produced by theconventional method, which interlayer consisted of a polyvinyl butyralsheet and, as formed on both sides thereof, concave and convex patterns(orderly) comprising a multiplicity of convex ridges (linear) triangularin cross-section and the corresponding multiplicity of convex troughs(linear), said troughs being not on the same level. The water content ofthis interlayer was adjusted to 0.4 to 0.5 weight %.

EXAMPLE 22

The surface of a metal roll was machined with an engraving mill (pyramidcup mill) to form a multiplicity of concave portions each in the form ofa quadrangular pyramid and the corresponding multiplicity of convexportions. The roll was further blasted with glass beads (#20) from adistance of about 30 cm at an air pressure of 100 kPa to fabricate anembossing roll.

Except that a pair of embossing rolls fabricated as above was used, theprocedure of Example 21 was otherwise repeated to manufacture aninterlayer comprising a polyvinyl butyral sheet and, as formed on bothsides thereof, concave and convex patterns (orderly) comprising amultiplicity of convex portions each in the form of a quadrangularpyramid and the corresponding multiplicity of concave portions, with therespective concave portions being not on the same level. In thisexample, the concave portion between adjacent convex portionsconstituted a grid-like trough.

EXAMPLE 23

The surface of a metal roll was machined with an engraving mill (wavytriangular oblique line cup mill) to form concave and convex patterns(not orderly) comprising a multiplicity of concave troughs (wavy)triangular in cross-section and the corresponding multiplicity ofcomplementary convex ridges (wavy). The roll was further blasted withglass beads (#20) from a distance of about 30 cm at an air pressure of 1kg to fabricate an embossing roll.

Except that a pair of embossing rolls fabricated in the above manner wasused, the procedure of Example 21 was otherwise repeated to produce aninterlayer comprising a polyvinyl butyral sheet and, as formed on bothsides thereof, concave and convex patterns (not orderly) comprising amultiplicity of convex ridges (wavy) triangular in cross-section and thecorresponding multiplicity of complementary concave troughs (wavy), withthe respective troughs being not on the same level.

COMPARATIVE EXAMPLE 6

The surface of a metal roll was machined with an engraving mill (lineartriangular oblique line cup mill) to form concave and convex patterns(orderly) comprising a multiplicity of concave troughs (linear)triangular in cross-section and the corresponding multiplicity ofcomplementary convex ridges (linear) to thereby fabricate an embossingroll.

Except that the above embossing roll was used, the procedure of Example21 was otherwise repeated to produce an interlayer comprising apolyvinyl butyral sheet and, as formed on both sides thereof, concaveand convex patterns (orderly) comprising a multiplicity of convex ridges(linear) triangular in cross-section and the corresponding multiplicityof complementary concave troughs (linear), with the respective concavetroughs being consistently on the same level.

For each of the interlayers obtained in the above Examples andComparative Example, the surface roughness (Rz) of the emboss design wasmeasured by the same method as used in Example 1 and the Rzv of thenegative model of the embossment was measured by the method describedbelow. Moreover, using these interlayers, laminated glass sheets weremanufactured by the following method and subjected to the same bake testas in Example 1 to evaluate deaeration and sealing performances in thepreliminary contact bonding stage. The results are collectively shown inTable 6.

[Measurement of Rzv]

Using the general-purpose molding silicone RTV KE-20 (product ofShin-Etsu Chemical), the emboss negative model was taken from each ofthe above interlayers and the surface roughness Rzv of this negativemodel was measured using the wedge-shaped tracer (tip width 1000 μm,opposite face angle 90°) by scanning with the tracer shifted in thedirection normal to its tip width in accordance with JIS B 0601.

[Evaluation of Deaeration and Sealing Performances]

Preliminary contact bonding was performed by the following alternativetechniques (draw deaeration and vacuum deaeration) and final contactdrawing was then performed to manufacture laminated glass sheets.

(a) Draw Deaeration Method

The interlayer was sandwiched between two sheets of transparent floatglass (30 cm long×30 cm wide×2 mm thick; the margin of each glass sheetwas curved by 1 mm with respect to the center) and the superfluous partof the interlayer was trimmed off. The resulting glass-interlayerassembly was heated in an oven until the temperature of the assembly(preliminary contact bonding temperature) had reached 60° C., 70° C. or80° C. And, then, passed over a pair of nip rollers (air cylinderpressure 350 kPa, linear velocity 10 m/min) for preliminary contactbonding.

(b) Vacuum Dearation

The interlayer was sandwiched between two sheets of transparent floatglass (30 cm long×30 cm wide×2 mm thick; the margin of each panel iscurved by 1 mm with respect of the center) and the superfluous part ofthe interlayer was trimmed off. The resulting glass-interlayer assemblywas transferred into a rubber bag and the rubber bag was connected to avacuum suction system. It was then heated externally and held at anegative pressure of −60 kPa (absolute pressure 16 kPa) for 10 minutes,the heating being carried out until the temperature of the assembly(preliminary contact bonding temperature) reached 60° C., 80° C. or 100°C. Then, the pressure was returned to atmospheric pressure to completepreliminary contact bonding.

The assemblies obtained by the above techniques (a) and (b) wererespectively held in an autoclave at a temperature of 140° C. And apressure of 1.3 MPa for 10 minutes, after which the temperature waslowered to 50° C. And the pressure returned to atmospheric pressure forfinal contact bonding to give laminated glass.

TABLE 6 Example 21 Example 22 Example 23 Compar. Ex. 6 Configuration ofconvex portion Triangular Quadrangular Triangular TriangularConfiguration of troughs Linear Grid Wavy Linear Arrangement OrderlyOrderly Not orderly Orderly Surface roughness of embossment, Rz (μm)48.5 46.4 52.1 53.4 Surface roughness of negative model, Rzv (μm) 12.212.9 13.6 9.5 Rzv/Rz 0.252 0.278 0.261 0.178 Preliminary contact bondingtemperature (° C.) Draw roll method 60 70 80 60 70 80 60 70 80 60 70 80Vacuum bag method 60 80 100 60 80 100 60 80 100 60 80 100 Bake test oflaminated glass (the number of sheets with air bubbles/100 sheets) Drawroll method 4 2 0 5 2 0 5 2 0 45 22 0 Vacuum bag method 3 1 0 2 2 0 4 10 15 6 0

As the thermoplastic resin sheet, DX film (product of Sekisui Chemical)was used.

Using a pair of rolls, namely a metal roll machined with a triangularoblique line mill (75 mesh, 80 depth, manufactured by Yuri Roll Co.) Anda rubber roll having a JIS hardness of 45 to 75, as the surfaceirregularity transfer device, the DX film was passed through the surfaceirregularity transfer device to form a trough-shaped embossment patternof continual concave portions on one side of the DX film. The transferconditions were as follows.

-   Temperature of DX film: room temperature-   Roll temperature: 140° C.-   Linear velocity: 10 m/min.-   Press linear pressure: 2500 kPa

Then, using a pair of rolls, namely a metal roll machined with saidtriangular oblique line mill and a reverse triangular oblique line mill(75 mesh, 80 depth, manufactured by Yuri Roll Co.), and a rubber rollhaving a JIS hardness of 45 to 75, as the surface irregularity transferdevice, the above-mentioned DX film formed with a trough pattern on oneside was passed through this surface irregularity transfer device toapply a grid-form segmenting pattern to the continual ridge pattern. Thetransfer conditions used here were as follows.

Temperature of DX film: room temperature

-   Roll temperature: 110° C.-   Linear velocity: 10 m/min.-   Press linear pressure: 2000 kPa

Then, the other side of the DX film was subjected to the same treatmentas above to give an interlayer for a laminated glass having anembossment pattern comprising embossed concave portions with a continualtrough-like geometry and embossed convex portions with segmentedportions on both sides.

EXAMPLE 25

Except that the transfer conditions for applying a grid-form segmentingpattern to the continual embossed convex portions were altered to thosementioned below, the procedure of Example 24 was otherwise repeated togive an interlayer for a laminated glass having an embossment patterncomprising embossed concave portions with continual trough-like geometryand embossed convex portions with segmented portions on both sides.

-   Temperature of DX film: room temperature-   Roll temperature: 120° C.-   Linear velocity: 10 m/min.-   Press linear pressure: 2000 kPa

EXAMPLE 26

Except that the following conditions (1) were used in the transferoperation for applying an embossment comprising continual trough-likegeometry of concave portions and the following conditions (2) in thetransfer operation for applying a grid-like segmenting pattern to thecontinual convex portion of the embossment, the procedure of Example 24was otherwise repeated to give an interlayer for a laminated glasshaving an embossment comprising embossed concave portions with continualtrough-like geometry and embossed convex portions with segmentedportions on both sides.

Condition (1)

-   Temperature of DX film: room temperature-   Roll temperature: 120° C.-   Linear velocity: 10 m/min.-   Press linear pressure: 2500 kPa    Condition (2)-   Temperature of DX film: room temperature-   Roll temperature: 130° C.-   Linear velocity: 10 m/min.-   Press linear pressure: 2000 kPa

COMPARATIVE EXAMPLE 7

Except that the grid-form segmenting pattern was not applied to thecontinual convex portion of the embossment, the procedure of Example 24was otherwise repeated to give an interlayer for a laminated glasshaving an embossment comprising embossed concave portion with acontinual trough-like geometry and embossed convex portions withoutsegmented portions on both sides.

The characteristics [(1) average surface roughness (Rz), (2) slip test,(3) antiblocking properties, (4) bake test] of the four kinds ofinterlayers for laminated glass as obtained in Examples 24 to 26 andComparative Example 7 were evaluated by the following methods. Theresults are shown in Table 7.

(1) Average Surface Roughness (Rz)

This parameter was measured in the same manner as in Example 1.

(2) Slip Test

The interlayer cut to 50 cm×50 cm was placed in horizontal position on asmooth-surfaced glass plate (50 cm long×50 cm wide) and a slip glasssheet (10 cm long×10 cm wide×2.5 mm thick) was placed in superposition.After 30 seconds, the slip glass sheet was pulled horizontally with aspring balance and the maximum frictional resistance was determined fromthe spring scale reading. The measurement was made in 5 replicates andthe average value was taken as maximum frictional resistance (g). Themeasurement was performed in an atmosphere of 20° C., 40% RH. Thesmaller the maximum frictional resistance value is, the superior is theslippage between the glass sheet and the interlayer, which means thatthe relative positioning of the glass sheet and the interlayer isfacilitated in the laminating operation and hence the handlingworkability is improved.

(3) Antiblocking Properties

Two sheets of the interlayer cut to 15 cm×15 cm were set one on theother and a weight of 13 kg was put on the sheets. After 24 hours ofstanding at room temperature, an angular peel test was performed using atensile tester at a pulling speed of 500 mm/min to measure the peelstrength. The measurement was carried out in 5 replicates and theaverage result was taken as peel strength (g). The smaller this peelstrength value is, the less ready is the sheet-to-sheet self-adhesion ofthe interlayer, which means superior antiblocking properties and betterworkability in storage and in the operation for interposing theinterlayer between glass sheets.

(4) Bake Test

Preliminary contact bonding was performed by the two alternativetechniques, viz. (a) draw deaeration and (b) vacuum deaeration, just asin Example 21, followed by final contact bonding to produce laminatedglass sheets and these sheets were subjected to the bake test.

TABLE 7 Example 24 Example 25 Example 26 Compar. Ex. 7 Embossment ofConcave Geometry Grid of troughs Grid of troughs Grid of troughs Lineartroughs interlayer portion Arrangement Orderly Orderly Orderly OrderlyConvex Segmentation Segmented Segmented Segmented Not segmented portionDepth of segmenting trough Shallow Slightly deep Deep — PerformanceAverage surface roughness (Rz: μm) 38.2 42.2 46.1 56.5 characteristicsof Slip properties (max. frictional resistance: g) 265 255 225 302interlayer Antiblocking properties (peel strength: g) 420 415 380 440Bake test Preliminary contact Draw deaeration 60 70 80 60 70 80 60 70 8060 70 80 bonding temperature (° C.) Vacuum deaeration 60 80 100 60 80100 60 80 100 60 80 100 the number of sheets with air Draw deaeration 21 0 4 1 0 6 2 0 20 10 0 bubbles/100 sheets Vacuum deaeration 1 0 0 2 1 04 3 0 25 15 0

It will be apparent from Table 7 that the intelayers for laminated glassaccording to Examples 24 to 26 of the invention invariably haveexcellent slip and antiblocking properties. This means that theseinterlayers provide for good workability in handing during storage andglass processing.

Furthermore, the laminated glass sheets of Examples 24 to 26 asmanufactured by using the interlayers according to Examples 24 to 26showed fewer sheets with air bubbles (fewer rejects) in the bake test,regardless of the preliminary contact bonding temperature used in thedraw deaeration process or in the vacuum deaeration process. Theseresults indicate good deaeration and sealing in the preliminary contactbonding stage.

In contrast, the laminated glass of Comparative Example 7 which wasmanufactured by using the interlayer for a laminated glass according toComparative Example 7 without providing segmentation to convex portionsof the embossment showed many sheets with air bubbles (many rejects) inthe bake test when the preliminary contact bonding temperature was low,whether in the draw deaeration process or in the vacuum deaerationprocess. This means that the sealing in the preliminary contact bondingstage was not wholesome, thus causing insufficient deaeration. Moreover,the result indicates that there are limitations on the manufacturingconditions which can be used in the preliminary contact bonding stage.

EXAMPLE 27

FIG. 20 shows an interlayer embodying the principles of the presentinvention, where (a) is a plan view and (b) is a side elevation view.

As shown in FIG. 20, the interlayer 1 of the invention comprises anextrusion-molded thermoplastic resin sheet provided with a plurality ofembossments 3 comprising fine concave portions and convex portions (notshown) on both sides and concave troughs 2 on one side, said concavetroughs 2 being disposed generally in parallel with the direction ofextrusion X of the thermoplastic resin sheet.

(Production of an Interlayer)

A thermoplastic resin sheet as obtained by extrusion of plasticizedpolyvinyl butyral resin (product of Sekisui Chemical; trade name “S-RecFilm DXN”, 760 μm thick) was passed through a surface irregularitytransfer device comprising a pair of rolls, namely a metal roll formedwith prismatic ridges (height: 120 μm, base 150 μm, pitch: 300 μm)complementary with the concave troughs 2 illustrated in FIG. 20 in axialcontinuum and random concave and convex patterns in the regions otherthan said ridges, and a rubber roll having a JIS hardness of 45 to 75with random concave and convex patterns, to fabricate an interlayerhaving concave troughs 2 each in a continuum parallel to the extrusiondirection of the sheet on one side thereof and embossed concave andconvex patterns on both sides. The transfer conditions used here were asfollows.

-   Temperature of DX film: room temperature-   Roll temperature: 120° C.-   Linear velocity: 10 m/min.-   Press linear pressure: 500 kPa

COMPARATIVE EXAMPLE 8

Except that the prismatic ridges of the metal roll were disposed at anangle of 45° with the axial direction, the procedure of Example 27 wasotherwise repeated to fabricate an interlayer.

COMPARATIVE EXAMPLE 9

Except that the prismatic ridges of the metal roll were disposed in thecircumferential direction, the procedure of Example 27 was otherwiserepeated to fabricate an interlayer.

COMPARATIVE EXAMPLE 10

Except that V-shaped concave troughs were provided in thecircumferential direction in lieu of the prismatic ridges of the metalroll, the procedure of Example 27 was otherwise repeated to fabricate aninterlayer.

The interlayers obtained in Example 27 and Comparative Examples 8 to 10were evaluated as follows.

(10-Point Average Surface Roughness {Rz (μm)})

This parameter was measured by the same method as in Example 1.

(Bake Test)

Preliminary contact bonding by the following alternative techniques, (a)draw deaeration and (b) vacuum deaeration, and final contact bondingwere serially carried out to manufacture laminated glass sheets.

(a) Draw Deaeration

The interlayer was sandwiched between two sheets of transparent floatglass (30 cm long×30 cm wide×2 mm thick; glass sheets with the margincurved by 1 mm with respect to the center) and the superfluous part wastrimmed off. The resulting assembly was heated in an oven until thetemperature of the assembly had reached 70° C., 80° C. or 90° C. And,then, passed over a nip roll (air cylinder pressure 35.5 MPa, linearvelocity 10 m/min) for preliminary contact bonding.

(b) Vacuum Deaeration

The interlayer was sandwiched between two sheets transparent float glass(30 cm long×30 cm wide×2 mm thick; glass sheets with the margin curvedby 1 mm with respect to the center) and the superfluous part was trimmedoff. The resulting assembly was transferred into a rubber bag and therubber bag was connected to a vacuum system. The assembly was heatedexternally under a negative pressure of −60 kPa (absolute pressure 16kPa) for 10 minutes until the temperature of the assembly (preliminarycontact bonding temperature) had reached 70° C., 80° C. or 90° C. Thepressure was then returned to atmospheric pressure to completepreliminary contact bonding.

The glass-interlayer assemblies subjected to preliminary contact bondingin the above processes (a) and (b), respectively, were held in anautoclave at a temperature of 140° C. And a pressure of 1.3 MPa for 10minutes, after which the temperature was lowered to 50° C. And thepressure returned to atmospheric pressure to complete final contactbonding to give laminated glass.

The laminated glass sheets obtained as above were subjected to the baketest under the same conditions as in Example 1.

TABLE 8 Example Compar. Ex. 27 8 9 10 10-point average surface roughness(μm) 35.5 37.8 40.2 64.2 Bake test Draw Temperature 70° C. 1 4 3 14 thenumber of deaeration 80° C. 1 2 4 8 sheets with air 90° C. 0 1 2 11bubbles/100 Vacuum Temperature 70° C. 0 0 1 1 sheets deaeration 80° C. 01 0 2 90° C. 1 0 1 0

EXAMPLE 28

The surface of a metal roll, blasted with #36 alumina to a surfaceroughness of about 60 μm, was coated with a lubricant and a geometrictransfer was made to the surface of a substrate interlayer sheet at 100°C. to give an interlayer having a random emboss pattern with a surfaceroughness of 30 μm. The surface of another metal roll was impressed witha triangular mill to form 200 μm-deep troughs on the surface of themetal roll and further impressed with a perpendicular triangular mill toprepare a roll surface reduced by 15 μm in depth of the troughs(corresponding to the bottom surface in the interlayer). Then, this rollsurface was geometrically transferred to the surface of the interlayerhaving said random embossment to give an interlayer having 40 μm-deep,80 μm-wide troughs at a pitch of 500 μm within 55 μm-deep, 60 μm-widetroughs formed at a trough pitch of 300 μm

EXAMPLE 29

Except that the pressure used for the geometric transfer of the metalroll surface to the substrate interlayer surface was altered, theprocedure of Example 28 was otherwise repeated to give an interlayerhaving a random embossment with a roughness of 30 μm as well as 50μm-deep, 70 μm-wide troughs formed at a pitch of 500 μm within 55μm-deep, 60 μm-wide troughs.

COMPARATIVE EXAMPLE 11

The pressure used for the geometric transfer of the metal roll surfaceto the substrate interlayer surface was altered and the troughs were notformed, the procedure of Example 28 was repeated to give an interlayerhaving a random-embossment with a surface roughness of 55 μm.

COMPARATIVE EXAMPLE 12

Except that the troughs were not formed, the procedure of Example 28 wasotherwise repeated to give an interlayer having a random embossment witha surface roughness of 30 μm.

COMPARATIVE EXAMPLE 13

A metal roll was machined to form the embossing pattern consisting of auniform array of quadrangular pyramids and the surface of this metalroll was geometrically transferred to a substrate interlayer sheetsurface to give an interlayer with a surface roughness of 70 μm.

COMPARATIVE EXAMPLE 14

Except that the pressure used for the geometric transfer of the metalroll surface to the interlayer sheet surface was altered, the procedureof Comparative Example 13 was otherwise repeated to give an interlayerwith a surface roughness of 35

COMPARATIVE EXAMPLE 15

The procedure of Example 28 was repeated to give an interlayer having arandom emboss pattern with a surface roughness of 30μm. Then, an ironroll surface with ridge-shaped troughs was constructed and a geometrictransfer was carried out from this roll surface to the interlayersurface having the above random embossment to give an interlayer having55 μm-deep, 60 μm-wide triangular wavy troughs at a pitch of 300 μm.

The performances (deaeration characteristics) of the interlayersobtained in the above Examples and Comparative Examples were evaluatedby the following method. The results are shown in Table 9.

(Evaluation of Deaeration Characteristic)

Each interlayer was sandwiched between two transparent 2 mm-thick glasssheets and the resulting glass-interlayer assembly was put in a rubberbag set to the initial temperature indicated in Table 9. The rubber bagwas connected to a vacuum suction system and the evacuation was started.The reduced pressure was maintained for about 10 minutes and theassembly was heated to the ultimate temperature indicated in Table 9.After cooling, the laminated glass was taken out and examined for airbubbles. The case in which no air bubble was found was rate O and thecase in which air bubbles were observed was rated X.

TABLE 9 Deaeration characteristic (inclusion of air bubbles) Initialtemperature (° C.) Ultimate temperature (° C.) 20 25 30 35 40 45 50 7075 80 85 90 95 100 Example 28 ◯ ◯ ◯ ◯ ◯ ◯ X X X X X ◯ ◯ ◯ 29 ◯ ◯ ◯ ◯ ◯ ◯X X X X X X ◯ ◯ Compar. Ex. 11 ◯ ◯ ◯ ◯ X X X X X X X ◯ ◯ ◯ 12 ◯ X X X XX X X ◯ ◯ ◯ ◯ ◯ ◯ 13 ◯ ◯ ◯ X X X X X X X ◯ ◯ ◯ ◯ 14 ◯ ◯ X X X X X X X ◯◯ ◯ ◯ ◯ 15 ◯ ◯ ◯ ◯ ◯ ◯ X X X X X X X ◯ ◯: No air bubble X: Air bubblesaccording to Examples of the invention, the evacuation initialtemperature can be set high and the ultimate temperature can be set low,so that an improved deaeration efficiency can be obtained in preliminarycontact bonding.

INDUSTRIAL APPLICABILITY

Because the present invention is constituted as described above, thereis no moiré phenomenon even when the arrangement and pitch of theembossment are orderly so that there can be provided an interlayer for alaminated glass with good workability in cutting and laminatingoperations and excellent deaeration characteristic in preliminarycontact bonding.

Furthermore, because of the above constitution of the invention, thetrouble of premature marginal sealing does not take place even if thedeaeration initial temperature in preliminary contact bonding is notcritically controlled so that an interlayer for a laminated glass withan excellent deaeration effect can be provided. Moreover, since theself-adhesion of the interlayer can be controlled, the interlayer hasgood handling characteristics.

Because of the very constitution described above, the invention providesan interlayer for a laminated glass which is not only good inworkability in terms of blocking resistance during storage and handlingin laminating work but also excellent in the deaeration and sealingcharacteristics in preliminary contact bonding. Therefore, particularlyin the manufacture of large-area or large-radius-of-curvature laminatedglass or for increased productivity of laminated glass production, bothdeaeration and sealing between the glass and interlayer are sufficientlyeffected so that the trouble of formation of air bubbles between theglass and interlayer due to infiltration of pressurized air through thesealing defect in the final contact bonding under heating and pressurein an autoclave and the consequent incidence of rejects can be largelyobviated, thus laminated glass products with particularly hightransparency can be obtained.

As a further advantage of the interlayer for a laminated glass accordingto the invention, satisfactory deaeration and sealing can be obtained inpreliminary contact bonding over a broad temperature range so that thecontrol of preliminary contact bonding temperature is facilitated andthe workability in laminating work is remarkably improved, with theresult that a variety of processing requirements of various users can besatisfied with ease and good efficiency.

Therefore, with the interlayer for a laminated glass according to theinvention, not only good workability is insured in the manufacture oflaminated glass products but there can be obtained laminated glass ofhigh quality substantially no incidence of rejects due to formation ofair bubbles even under stringently restricted manufacturing conditions.

The laminated glass products manufactured by using the interlayer for alaminated glass according to the invention is of high quality almostfree of the air bubble problem even when manufactured under rigorouslyrestricted conditions and can be used with advantage in the glazing ofthe windows of cars, rolling stock, aircraft, buildings and so forth.

1. An interlayer for a laminated glass which comprises a thermoplasticresin sheet provided with embossments comprising concave portions andconvex portions on both sides thereof, said concave portions on at leastone side having a trough-like geometry, and segmenting walls beingformed in said trough-like geometry, thereby obviating an occurrence ofa seal defect, wherein the thermoplastic resin sheet is a plasticizedpolyvinyl acetal resin sheet.
 2. The interlayer for a laminated glassaccording to claim 1, wherein a height of the segmenting wall is smallerthan a depth of the trough.
 3. The interlayer for a laminated glassaccording to claim 2, wherein the segmenting walls are arranged at equalintervals.
 4. The interlayer for a laminated glass according to claim 1,wherein the trough-like geometry is constant in sectional area while thesegmenting wall has a depth distribution of troughs having a depth ofnot less than 5% of the maximum trough depth.
 5. The interlayer for alaminated glass according to claim 4, wherein troughs having the depthof not less than 5% of the maximum trough depth are provided at a pitchof not more than 10 mm.
 6. The interlayer for a laminated glassaccording to claim 4, wherein the trough-like geometry is provided inparallel with the direction of flow of the interlayer for a laminatedglass.
 7. A laminated glass obtainable by interposing the interlayer forthe laminated glass according to claim 1 between at least one pair ofglass sheets and consolidating them into an integral unit.